1 of 1
                                FORM 10-Q

                    SECURITIES AND EXCHANGE COMMISSION
                         WASHINGTON, D.C.  20549

(MARK ONE)

(X)  QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d)
     OF THE SECURITIES EXCHANGE ACT OF 1934

For the quarterly period ended March 31, 2004

                                    OR

( )  TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d)
     OF THE SECURITIES EXCHANGE ACT OF 1934

For the transition period from ________________ to ________________

Commission File Number 0-20298

         SOUTHWEST ROYALTIES INSTITUTIONAL 1990-91 INCOME PROGRAM
         Southwest Royalties Institutional Income Fund X-C, L.P.
                  (Exact name of registrant as specified
                  in its limited partnership agreement)

Delaware                                75-2374449
(State or other jurisdiction of                (I.R.S. Employer
incorporation or organization)                Identification No.)


                       407 N. Big Spring, Suite 300
                           Midland, Texas 79701
                 (Address of principal executive offices)

                              (432) 686-9927
                      (Registrant's telephone number,
                           including area code)

Indicate  by  check  mark  whether registrant (1)  has  filed  all  reports
required to be filed by Section 13 or 15(d) of the Securities Exchange  Act
of 1934 during the preceding 12 months (or for such shorter period that the
registrant was required to file such reports), and (2) has been subject  to
such filing requirements for the past 90 days:

                              Yes X No ___

Indicate  by check mark whether the registrant is an accelerated filer  (as
defined in Exchange Act Rule 12b-2).     Yes     No  X

The  registrant's  outstanding  securities  consist  of  Units  of  limited
partnership  interests for which there exists no established public  market
from which to base a calculation of aggregate market value.

        The total number of pages contained in this report is 22.

<PAGE>
Glossary of Oil and Gas Terms
The  following are abbreviations and definitions of terms commonly used  in
the  oil  and  gas industry that are used in this filing.  All  volumes  of
natural gas referred to herein are stated at the legal pressure base to the
state  or area where the reserves exit and at 60 degrees Fahrenheit and  in
most instances are rounded to the nearest major multiple.

     Bbl. One stock tank barrel, or 42 United States gallons liquid volume.

     Developmental well. A well drilled within the proved area of an oil or
natural gas reservoir to the depth of a stratigraphic horizon known  to  be
productive.

     Exploratory well. A well drilled to find and produce oil or gas in  an
unproved  area to find a new reservoir in a field previously  found  to  be
productive of oil or natural gas in another reservoir or to extend a  known
reservoir.

     Farm-out  arrangement. An agreement whereby the owner of the leasehold
or  working  interest  agrees to assign his interest  in  certain  specific
acreage  to  the assignee, retaining some interest, such as  an  overriding
royalty interest, subject to the drilling of one (1) or more wells or other
performance by the assignee.

     Field. An area consisting of a single reservoir or multiple reservoirs
all  grouped  on  or  related to the same individual geological  structural
feature and/or stratigraphic condition.

     Mcf. One thousand cubic feet.

     Net  Profits  Interest.  An agreement whereby  the  owner  receives  a
specified  percentage of the defined net profits from a producing  property
in  exchange for consideration paid.  The net profits interest  owner  will
not otherwise participate in additional costs and expenses of the property.

     Oil. Crude oil, condensate and natural gas liquids.

     Overriding  royalty  interest. Interests that  are  carved  out  of  a
working  interest, and their duration is limited by the term of  the  lease
under which they are created.

<PAGE>
     Present  value  and  PV-10 Value. When used with respect  to  oil  and
natural gas reserves, the estimated future net revenue to be generated from
the  production of proved reserves, determined in all material respects  in
accordance  with  the  rules and regulations of the  SEC  (generally  using
prices  and costs in effect as of the date indicated) without giving effect
to  non-property  related  expenses  such  as  general  and  administrative
expenses,  debt service and future income tax expenses or to  depreciation,
depletion  and  amortization, discounted using an annual discount  rate  of
10%.

     Production  costs.  Costs incurred to operate and maintain  wells  and
related  equipment  and facilities, including depreciation  and  applicable
operating  costs  of support equipment and facilities and  other  costs  of
operating and maintaining those wells and related equipment and facilities.

     Proved Area. The part of a property to which proved reserves have been
specifically attributed.

     Proved  developed oil and gas reserves. Proved developed oil  and  gas
reserves  are  reserves that can be expected to be recovered from  existing
wells with existing equipment and operating methods.

     Proved properties. Properties with proved reserves.

     Proved  reserves. The estimated quantities of crude oil, natural  gas,
and  natural  gas liquids that geological and engineering data  demonstrate
with  reasonable  certainty to be recoverable in future  years  from  known
reservoirs under existing economic and operating conditions.

     Proved  undeveloped reserves. Proved undeveloped oil and gas  reserves
are  reserves that are expected to be recovered from new wells on undrilled
acreage,  or  from existing wells where a relatively major  expenditure  is
required for recompletion.

     Reservoir.  A porous and permeable underground formation containing  a
natural  accumulation  of  producible  oil  or  gas  that  is  confined  by
impermeable  rock  or water barriers and is individual  and  separate  from
other reservoirs.

     Royalty  interest.  An  interest in an oil and  natural  gas  property
entitling  the  owner to a share of oil or natural gas production  free  of
costs of production.

     Working  interest.  The operating interest that gives  the  owner  the
right  to  drill, produce and conduct operating activities on the  property
and a share of production.

     Workover.  Operations  on  a producing well  to  restore  or  increase
production.

<PAGE>
                     PART I. - FINANCIAL INFORMATION


Item 1.   Financial Statements

The  unaudited  condensed financial statements included  herein  have  been
prepared  by  the Registrant (herein also referred to as the "Partnership")
in  accordance  with generally accepted accounting principles  for  interim
financial information and with the instructions to Form 10-Q and Rule 10-01
of Regulation S-X.  Accordingly, they do not include all of the information
and  footnotes  required  by generally accepted accounting  principles  for
complete   financial  statements.   In  the  opinion  of  management,   all
adjustments necessary for a fair presentation have been included and are of
a  normal  recurring nature.  The financial statements should  be  read  in
conjunction with the audited financial statements and the notes thereto for
the  year ended December 31, 2003, which are found in the Registrant's Form
10-K  Report  for  2003 filed with the Securities and Exchange  Commission.
The December 31, 2003 balance sheet included herein has been taken from the
Registrant's 2003 Form 10-K Report.  Operating results for the three  month
period  ended March 31, 2004 are not necessarily indicative of the  results
that may be expected for the full year.





<PAGE>
         Southwest Royalties Institutional Income Fund X-C, L.P.
                              Balance Sheets

                                  March    December
                                   31,       31,
                                   2004      2003
                                   ----      ----
                                 (unaudit
                                   ed)
Assets
----------

Current assets:
 Cash and cash equivalents    $  24,254    26,631
  Receivable  from  Managing     87,252    40,531
General Partner
                                 --------  --------
                                 ----      ----
   Total current assets          111,506   67,162
                                 --------  --------
                                 ----      ----
Oil  and  gas  properties  -
using the full-
 method of accounting            2,395,60  2,395,60
                                 1         1
       Less      accumulated
depreciation,
         depletion       and     2,231,14  2,228,14
amortization                     3         3
                                 --------  --------
                                 ----      ----
      Net   oil   and    gas     164,458   167,458
properties
                                 --------  --------
                                 ----      ----
                              $  275,964   234,620
                                 =======   =======
Liabilities  and   Partners'
Equity
----------------------------
-----------

Asset retirement obligation   $  755,662   740,845
                                 --------  --------
                                 ----      ----

Partners' equity:
 General partners                (89,502)  (92,455)
 Limited partners                (390,196  (413,770
                                 )         )
                                 --------  --------
                                 ----      ----
   Total partners' equity        (479,698  (506,225
                                 )         )
                                 --------  --------
                                 ----      ----
                              $  275,964   234,620
                                 =======   =======

<PAGE>
         Southwest Royalties Institutional Income Fund X-C, L.P.
                         Statements of Operations
                               (unaudited)

                                        Three Months Ended
                                            March 31,
                                         2004        2003
                                         ----        ----
Revenues
-------------
    Income   from   net   profits  $  91,227      76,029
interests
 Interest                             43          52
 Other                                250         -
                                      ----------  ---------
                                                  -
                                      91,520      76,081
                                      ----------  ---------
                                                  -
Expenses
------------
 General and administrative           12,569      10,235
   Depreciation,  depletion   and     3,000       12,000
amortization
  Accretion  of asset  retirement     14,817      16,270
obligation
                                      ----------  ---------
                                                  -
                                      30,386      38,505
                                      ----------  ---------
                                                  -
Net    income   from    continued     61,134      37,576
operations

Results     from     discontinued
operations -
 sale of oil and gas leases - See     (4,607)     4,153
Note 4
                                      ----------  ---------
                                                  -
Net   income   before  cumulative
effect
 of accounting change                 56,527      41,729

Cumulative  effect of  change  in
accounting
  principle - SFAS No. 143 -  See     -           (599,030)
Note 3
                                      ----------  ---------
                                                  -
Net income (loss)                  $  56,527      (557,301)
                                      ======      ======
Net income (loss) allocated to:

 Managing General Partner          $  5,357       (49,077)
                                      ======      ======
 General partner                   $  596         (5,453)
                                      ======      ======
 Limited partners                  $  50,574      (502,771)
                                      ======      ======
     Per   limited  partner  unit
before discontinued
     operations  and   cumulative  $    9.15           5.45
effect
    Discontinued  operations  per      (.69)         .61
limited partner unit
   Cumulative effect per  limited          -
partner unit                                      (90.11)
                                      ----------  ---------
                                                  -
  Per limited partner unit         $    8.46      (84.05)
                                      ======      ======
<PAGE>
         Southwest Royalties Institutional Income Fund X-C, L.P.

                         Statements of Cash Flows
                               (unaudited)

                                      Three Months Ended
                                           March 31,
                                        2004       2003
                                       -----       ----
Cash    flows   from    operating
activities:

  Cash  received from net profits  $ 43,443     48,364
interest
 Cash paid to suppliers              (11,506)   (6,760)
 Discontinued operations             (4,607)    4,153
 Interest received                   43         52
 Other                               250        -
                                     ---------  ---------
                                     -          -
   Net cash provided by operating    27,623     45,809
activities
                                     ---------  ---------
                                     -          -
Cash  flows provided by investing
activities:

 Sale of oil and gas properties      -          7,000
                                     ---------  ---------
                                     -          -
Cash   flows  used  in  financing
activities:

 Distributions to partners           (30,000)   (50,000)
                                     ---------  ---------
                                     -          -
Net  (decrease) increase in  cash    (2,377)    2,809
and cash equivalents

 Beginning of period                 26,631     20,887
                                     ---------  ---------
                                     -          -
 End of period                     $ 24,254     23,696
                                     ======     ======
Reconciliation  of   net   income
(loss) to net cash
     provided     by    operating
activities:

Net income (loss)                  $ 56,527     (557,301)

Adjustments   to  reconcile   net
income (loss) to
  net  cash provided by operating
activities:

   Depreciation,  depletion   and    3,000      12,000
amortization
  Accretion  of asset  retirement    14,817     16,270
obligation
  Cumulative effect of change  in
accounting
  principle - SFAS No. 143           -          599,030
 Increase in receivables             (47,784)   (27,665)
 Increase in payables                1,063      3,475
                                     ---------  ---------
                                     -          -
Net  cash  provided by  operating  $ 27,623     45,809
activities
                                     ======     ======
Noncash  investing and  financing
activities:

   Increase   in  oil   and   gas
properties - Adoption
  of SFAS No.143                   $ -          214,465
                                     ======     ======

<PAGE>
         Southwest Royalties Institutional Income Fund X-C, L.P.
                     (a Delaware limited partnership)

                      Notes to Financial Statements

1.   Organization
     Southwest  Royalties Institutional Income Fund X-C, L.P. was organized
     under the laws of the state of Delaware on September 20, 1991, for the
     purpose  of acquiring producing oil and gas properties and to  produce
     and market crude oil and natural gas produced from such properties for
     a  term  of 50 years, unless terminated at an earlier date as provided
     for  in the Partnership Agreement.  The Partnership sells its oil  and
     gas production to several purchasers with the prices it receives being
     dependent  upon  the oil and gas economy.  Southwest  Royalties,  Inc.
     serves as the Managing General Partner and H. H. Wommack, III, as  the
     individual   general  partner.   Revenues,  costs  and  expenses   are
     allocated as follows:

                         Limited   General
                         Partners  Partners
                         --------  --------
Interest   income    on    100%       -
capital contributions
Oil and gas sales          90%       10%
All other revenues         90%       10%
Organization        and    100%       -
offering costs (1)
Syndication costs          100%       -
Amortization         of    100%       -
organization costs
Property    acquisition    100%       -
costs
Gain/loss  on  property    90%       10%
disposition
Operating           and    90%       10%
administrative    costs
(2)
Depreciation, depletion
and amortization
   of   oil   and   gas    100%       -
properties
All other costs            90%       10%

          (1)   All  organization costs in excess of 3% of initial  capital
          contributions  will be paid by the Managing General  Partner  and
          will  be treated as a capital contribution.  The Partnership paid
          the  Managing  General Partner an amount equal to 3%  of  initial
          capital contributions for such organization costs.

          (2)  Administrative costs in any year, which exceed 2% of capital
          contributions shall be paid by the Managing General  Partner  and
          will be treated as a capital contribution.

2.   Summary of Significant Accounting Policies
     The  interim financial information as of March 31, 2004, and  for  the
     three  months ended March 31, 2004, is unaudited.  Certain information
     and  footnote  disclosures normally included in  financial  statements
     prepared  in accordance with generally accepted accounting  principles
     have been condensed or omitted in this Form 10-Q pursuant to the rules
     and  regulations of the Securities and Exchange Commission.   However,
     in  the  opinion  of  management, these interim  financial  statements
     include all the necessary adjustments to fairly present the results of
     the interim periods and all such adjustments are of a normal recurring
     nature.  The interim consolidated financial statements should be  read
     in  conjunction with the Partnership's Annual Report on Form 10-K  for
     the year ended December 31, 2003.

<PAGE>
         Southwest Royalties Institutional Income Fund X-C, L.P.
                     (a Delaware limited partnership)

                      Notes to Financial Statements

3.   Cumulative effect of change in accounting principle - SFAS No. 143
     On  January  1, 2003, the Partnership adopted Statement  of  Financial
     Accounting   Standards  No.  143,  Accounting  for  Asset   Retirement
     Obligations  ("SFAS No. 143").  Adoption of SFAS No. 143  is  required
     for  all  companies with fiscal years beginning after June  15,  2002.
     The new standard requires the Partnership to recognize a liability for
     the  present  value  of  all  legal obligations  associated  with  the
     retirement  of tangible long-lived assets and to capitalize  an  equal
     amount as a cost of the asset and depreciate the additional cost  over
     the  estimated  useful  life of the asset.  On January  1,  2003,  the
     Partnership    recorded   additional   costs,   net   of   accumulated
     depreciation,  of  approximately $214,465, a long  term  liability  of
     approximately  $813,495 and a loss of approximately $599,030  for  the
     cumulative  effect  on  depreciation  of  the  additional  costs   and
     accretion  expense  on  the liability related to expected  abandonment
     costs  of its oil and natural gas producing properties.  At March  31,
     2004,  the  asset retirement obligation was $755,662. The decrease  in
     the  balance  from  January 1, 2004 is due  to  accretion  expense  of
     $14,817.

4.   Discontinued Operations - Sale of oil and gas leases
     During 2003, the Partnership sold its interest in certain oil and  gas
     wells  for  $81,184  sales  proceeds and  retired  $100,007  of  asset
     retirement  obligation  associated with  the  properties.   Since  the
     Partnership  is  under the full cost pool method  of  accounting,  the
     sales  proceeds and asset retirement obligation liability  were  taken
     against  the  oil and gas properties asset account and  therefore,  no
     gain or loss was recorded and shown on the statement of operations  as
     part  of  the  discontinued operations. Operating  expenses  for  2004
     represent  plugging  and abandonment costs that  the  Partnership  was
     contractually committed to perform prior to the sale of the  property.
     Plugging  and abandonment services were performed during  the  quarter
     ended  March 31, 2004.  Pursuant to the requirements of SFAS No.  144,
     the  operating  results from these properties have  been  reported  as
     discontinued operations in the accompanying statements of operations.

     The   following   table   summarizes  certain   historical   operating
     information related to the discontinued operations:

                  Three months ended
                       March 31,
                    2004       2003

Income from net
profit
   interest       $(4,607)   4,153

5.   Subsequent Event
     Subsequent  to  December  31,  2003,  the  Managing  General   Partner
     announced that its Board of Directors had decided to explore a  merger
     or  sale  of  the  stock of the Company.  The Board formed  a  Special
     Committee  of independent directors to oversee the sale process.   The
     Special Committee retained independent financial and legal advisors to
     work closely with management to implement the sale process.

     On  May  3,  2004, the Managing General Partner entered  into  a  cash
     merger  agreement to sell all of its stock to Clayton Williams Energy,
     Inc.  The cash merger price is being negotiated, but is expected to be
     approximately  $45 per share.  The transaction, which  is  subject  to
     approval  by the Managing General Partner's shareholders, is  expected
     to close no later than May 21, 2004.


<PAGE>
Item 2.   Management's  Discussion and Analysis of Financial Condition  and
          Results of Operations

General

Southwest Royalties Institutional Income Fund X-C, L.P. was organized as  a
Delaware limited partnership on September 20, 1991.  The offering  of  such
limited  partnership interests began October 1, 1991 as  part  of  a  shelf
offering registered under the name Southwest Royalties Institutional  1990-
91  Income Program.  Minimum capital requirements for the Partnership  were
met on January 28, 1992, with the offering of limited partnership interests
concluding April 30, 1992.

The Partnership was formed to acquire royalty and net profits interests  in
producing  oil  and  gas properties, to produce and market  crude  oil  and
natural  gas  produced  from such properties, and  to  distribute  the  net
proceeds from operations to the limited and general partners.  Net revenues
from  producing  oil  and gas properties will not be  reinvested  in  other
revenue  producing  assets except to the extent that production  facilities
and wells are improved or reworked or where methods are employed to improve
or  enable  more efficient recovery of oil and gas reserves.  The  economic
life  of  the  Partnership  thus  depends on  the  period  over  which  the
Partnership's oil and gas reserves are economically recoverable.

Increases   or   decreases   in  Partnership   revenues   and,   therefore,
distributions  to partners will depend primarily on changes in  the  prices
received  for  production,  changes in volumes of  production  sold,  lease
operating  expenses, enhanced recovery projects, offset drilling activities
pursuant  to farm-out arrangements, sales of properties, and the  depletion
of  wells.   Since  wells deplete over time, production  can  generally  be
expected to decline from year to year.

Well  operating costs and general and administrative costs usually decrease
with   production   declines;  however,  these  costs  may   not   decrease
proportionately.  Net income available for distribution to the partners  is
therefore expected to decline in later years based on these factors.

Based on current conditions, management anticipates performing no workovers
during  2004  to  enhance  production.  The partnership  will  most  likely
continue  to  experience  the  historical  production  decline,  which  has
approximated  10%  per  year.   Accordingly,  if  commodity  prices  remain
unchanged,  the  Partnership  expects future earnings  to  decline  due  to
anticipated production declines.

Oil and Gas Properties

Oil  and  gas  properties  are accounted for at cost  under  the  full-cost
method.  Under this method, all productive and nonproductive costs incurred
in  connection with the acquisition, exploration and development of oil and
gas  reserves  are capitalized.  Gain or loss on the sale of  oil  and  gas
properties  is not recognized unless significant oil and gas  reserves  are
sold.

In  2002,  the  Partnership changed methods of accounting for depletion  of
capitalized  costs  from  the  units-of-revenue  method  to  the  units-of-
production method.  The newly adopted accounting principle is preferable in
the  circumstances  because the units-of-production  method  results  in  a
better  matching of the costs of oil and gas production against the related
revenue received in periods of volatile prices for production as have  been
experienced  in  recent  periods.   Additionally,  the  units-of-production
method is the predominant method used by full cost companies in the oil and
gas  industry,  accordingly, the change improves the comparability  of  the
Partnership's financial statements with its peer group.

Should the net capitalized costs exceed the estimated present value of  oil
and gas reserves, discounted at 10%, such excess costs would be charged  to
current  expense. As of March 31, 2004, the net capitalized costs  did  not
exceed the estimated present value of oil and gas reserves.


<PAGE>
The  Partnership's  interest  in oil and gas  properties  consists  of  net
profits  interests  in  proved properties located  within  the  continental
United  States.   A net profits interest is created when  the  owner  of  a
working  interest in a property enters into an arrangement  providing  that
the  net profits interest owner will receive a stated percentage of the net
profit  from  the  property.   The  net profits  interest  owner  will  not
otherwise participate in additional costs and expenses of the property.

The  Partnership recognizes income from its net profits interest in oil and
gas property on an accrual basis, while the quarterly cash distributions of
the net profits interest are based on a calculation of actual cash received
from  oil  and  gas sales, net of expenses incurred during  that  quarterly
period.  If  the  net  profits  interest calculation  results  in  expenses
incurred  exceeding the oil and gas income received during  a  quarter,  no
cash  distribution is due to the Partnership's net profits  interest  until
the  deficit is recovered from future net profits.  The Partnership accrues
a quarterly loss on its net profits interest provided there is a cumulative
net  amount  due for accrued revenue as of the balance sheet date.   As  of
March  31,  2004,  there were no timing differences, which  resulted  in  a
deficit net profit interest.

Critical Accounting Policies

Full cost ceiling calculations The Partnership follows the full cost method
of  accounting  for  its  oil and gas properties.   The  full  cost  method
subjects  companies to quarterly calculations of a "ceiling", or limitation
on  the  amount of properties that can be capitalized on the balance sheet.
If  the  Partnership's capitalized costs are in excess  of  the  calculated
ceiling, the excess must be written off as an expense.

The  Partnership's discounted present value of its proved oil  and  natural
gas  reserves  is  a  major  component  of  the  ceiling  calculation,  and
represents  the  component  that requires the  most  subjective  judgments.
Estimates  of  reserves are forecasts based on engineering data,  projected
future  rates  of  production and the timing of future  expenditures.   The
process  of  estimating oil and natural gas reserves  requires  substantial
judgment,  resulting  in  imprecise determinations,  particularly  for  new
discoveries.   Different reserve engineers may make different estimates  of
reserve  quantities  based  on the same data.   The  Partnership's  reserve
estimates are prepared by outside consultants.  Quarterly reserve estimates
are prepared by the Managing General Partner's internal staff of engineers.

The  passage  of  time  provides  more  qualitative  information  regarding
estimates of reserves, and revisions are made to prior estimates to reflect
updated  information.   However,  there  can  be  no  assurance  that  more
significant  revisions  will not be necessary in  the  future.   If  future
significant  revisions  are  necessary  that  reduce  previously  estimated
reserve quantities, it could result in a full cost property writedown.   In
addition to the impact of these estimates of proved reserves on calculation
of  the  ceiling,  estimates  of proved reserves  are  also  a  significant
component of the calculation of DD&A.

While  the quantities of proved reserves require substantial judgment,  the
associated prices of oil and natural gas reserves that are included in  the
discounted  present  value of the reserves do not  require  judgment.   The
ceiling calculation dictates that prices and costs in effect as of the last
day  of  the  period are generally held constant indefinitely. Because  the
ceiling  calculation dictates that prices in effect as of the last  day  of
the  applicable quarter are held constant indefinitely, the resulting value
is  not indicative of the true fair value of the reserves.  Oil and natural
gas  prices have historically been cyclical and, on any particular  day  at
the  end of a quarter, can be either substantially higher or lower than the
Partnership's  long-term price forecast that is a barometer for  true  fair
value.

In  2002,  the  Partnership changed methods of accounting for depletion  of
capitalized  costs  from  the  units-of-revenue  method  to  the  units-of-
production method.  The newly adopted accounting principle is preferable in
the  circumstances  because the units-of-production  method  results  in  a
better  matching of the costs of oil and gas production against the related
revenue received in periods of volatile prices for production as have  been
experienced  in  recent  periods.   Additionally,  the  units-of-production
method is the predominant method used by full cost companies in the oil and
gas  industry,  accordingly, the change improves the comparability  of  the
Partnership's financial statements with its peer group.


<PAGE>
Results of Operations

A.  General Comparison of the Quarters Ended March 31, 2004 and 2003

The  following  table  provides certain information  regarding  performance
factors for the quarters ended March 31, 2004 and 2003.

                               Three Months
                                  Ended         Percenta
                                                   ge
                                March 31,       Increase
                              2004      2003    (Decreas
                                                   e)
                             -----     -----    --------
                                                   --
Average    price    per  $   31.03              -
barrel of oil                         31.06
Average  price per  mcf  $    4.56              (12%)
of gas                                5.21
Oil    production    in     5,710     6,390     (11%)
barrels
Gas production in mcf       5,800     5,470     6%
Income from net profits  $  91,227    76,029    20%
interests
Partnership              $  30,000    50,000    (40%)
distributions
Limited         partner  $  27,000    45,000    (40%)
distributions
Per  unit  distribution
to limited
 partners                $    4.51              (40%)
                                      7.52

Number    of    limited     5,983     5,983
partner units

Revenues

The  Partnership's income from net profits interests increased  to  $91,227
from  $76,029 for the quarters ended March 31, 2004 and 2003, respectively,
an  increase of 20%. The principal factors affecting the comparison of  the
quarters ended March 31, 2004 and 2003 are as follows:

1.  The  average  price  for a barrel of oil received  by  the  Partnership
    decreased  during the quarter ended March 31, 2004 as compared  to  the
    quarter  ended  March  31, 2003 by less than 1%, or  $.03  per  barrel,
    resulting  in  a  decrease of approximately $200  in  income  from  net
    profits  interests.  Oil sales represented 87% of  total  oil  and  gas
    sales during the quarter ended March 31, 2004 as compared to 87% during
    the quarter ended March 31, 2003.

    The  average  price  for  an  mcf of gas received  by  the  Partnership
    decreased during the same period by 12%, or $.65 per mcf, resulting  in
    a   decrease  of  approximately  $3,800  in  income  from  net  profits
    interests.

    The  total  decrease in income from net profits interests  due  to  the
    change  in prices received from oil and gas production is approximately
    $4,000.   The market price for oil and gas has been extremely  volatile
    over  the  past  decade, and management expects  a  certain  amount  of
    volatility to continue in the foreseeable future.

<PAGE>
2.  Oil  production decreased approximately 680 barrels or 11%  during  the
    quarter ended March 31, 2004 as compared to the quarter ended March 31,
    2003,  resulting in a decrease of approximately $21,100 in income  from
    net profits interests.

    Gas  production increased approximately 330 mcf or 6% during  the  same
    period, resulting in an increase of approximately $1,700 in income from
    net profits interests.

    The  net total decrease in income from net profits interests due to the
    change  in  production is approximately $19,400.  The decrease  in  oil
    volumes is due to production declines on two properties.

3.  Lease  operating  costs  and  production  taxes  were  26%  lower,   or
    approximately $38,700 less during the quarter ended March 31,  2004  as
    compared to the quarter ended March 31, 2003.  Lease operating expenses
    were  higher in 2003 as a result of electricity credits on one property
    in 2004, plug and abandonment costs for a well in 2003 and replacing  a
    tank on a salt water disposal facility in 2003.

Costs and Expenses

Total costs and expenses decreased to $30,386 from $38,505 for the quarters
ended  March  31,  2004  and 2003, respectively, a decrease  of  21%.   The
decrease is a direct result of the decrease in accretion expense associated
with  our long term liability related to expected abandonment costs of  our
oil  and natural gas properties and depletion expense, partially offset  by
an increase in general and administrative expense.

1.  General and administrative costs consists of independent accounting and
    engineering  fees,  computer services, postage,  and  Managing  General
    Partner  personnel costs.  General and administrative  costs  increased
    23% or approximately $2,300 during the quarter ended March 31, 2004  as
    compared to the quarter ended March 31, 2003.  The increase in  general
    and   administrative  costs  is  due  primarily  to  an   increase   of
    approximately $1,660 in quarterly accounting review fees.

2.  Depletion  expense decreased to $3,000 for the quarter ended March  31,
    2004  from  $12,000  for  the same period in 2003.  This  represents  a
    decrease  of 75%.  The contributing factor to the decrease in depletion
    expense is in relation to the BOE depletion rate for the quarter  ended
    March  31,  2004, which was $.45 applied to 6,677 BOE  as  compared  to
    $1.64 applied to 7,302 BOE for the same period in 2003.

Cumulative effect of change in accounting principle

On  January  1,  2003,  the  Partnership  adopted  Statement  of  Financial
Accounting  Standards No. 143, Accounting for Asset Retirement  Obligations
("SFAS  No. 143").  Adoption of SFAS No. 143 is required for all  companies
with fiscal years beginning after June 15, 2002.  The new standard requires
the Partnership to recognize a liability for the present value of all legal
obligations  associated with the retirement of tangible  long-lived  assets
and to capitalize an equal amount as a cost of the asset and depreciate the
additional cost over the estimated useful life of the asset.  On January 1,
2003,  the  Partnership  recorded  additional  costs,  net  of  accumulated
depreciation,  of  approximately  $214,465,  a  long  term   liability   of
approximately  $813,495  and  a  loss of  approximately  $599,030  for  the
cumulative  effect  on depreciation of the additional costs  and  accretion
expense  on the liability related to expected abandonment costs of its  oil
and  natural  gas  producing  properties.  At March  31,  2004,  the  asset
retirement  obligation  was  $755,662. The decrease  in  the  balance  from
January 1, 2004 is due to accretion expense of $14,817.

<PAGE>
Liquidity and Capital Resources

The  primary source of cash is from operations, the receipt of income  from
interests in oil and gas properties.  The Partnership knows of no  material
change, nor does it anticipate any such change.

Cash  flows provided by operating activities were approximately $27,600  in
the  quarter ended March 31, 2004 as compared to approximately  $45,800  in
the quarter ended March 31, 2003.

There  were no cash flows used in investing activities in the quarter ended
March  31,  2004.   Cash  flows  provided  by  investing  activities   were
approximately $7,000 in the quarter ended March 31, 2003.

Cash  flows used in financing activities were approximately $30,000 in  the
quarter ended March 31, 2004.  Cash flows used in financing activities were
approximately $50,000 in the quarter ended March 31, 2003.  The only use in
financing activities was the distributions to partners.

Total distributions during the quarter ended March 31, 2004 were $30,000 of
which  $27,000  was distributed to the limited partners and $3,000  to  the
general partners.  The per unit distribution to limited partners during the
quarter  ended  March 31, 2004 was $4.51.  Total distributions  during  the
quarter  ended March 31, 2003 were $50,000 of which $45,000 was distributed
to  the limited partners and $5,000 to the general partners.  The per  unit
distribution  to limited partners during the quarter ended March  31,  2003
was $7.52.

The  primary sources for the 2004 distributions of $30,000 were oil and gas
operations  of approximately $27,600, with the balance from available  cash
on  hand at the beginning of the period.  The primary sources for the  2003
distributions  of  $50,000  were oil and gas  operations  of  approximately
$45,800  and the change in oil and gas properties of approximately  $7,000,
resulting  in  excess cash for contingencies or subsequent distribution  to
partners.

Cumulative  cash distributions of $3,477,838 have been made to the  general
and  limited  partners.  As of March 31, 2004, $3,147,875  or  $526.14  per
limited  partner  unit  has  been  distributed  to  the  limited  partners,
representing  a  100%  return  of  capital  and  a  5%  return  on  capital
contributed.

As of March 31, 2004, the Partnership had approximately $111,500 in working
capital.   The  Managing  General Partner knows of no  unusual  contractual
commitments.  Although the partnership held many long-lived  properties  at
inception,  because of the restrictions on property development imposed  by
the partnership agreement, the Partnership cannot develop its non-producing
properties, if any.  Without continued development, the producing  reserves
continue  to  deplete.  Accordingly, as the Partnership's  properties  have
matured  and  depleted,  the  net  cash  flows  from  operations  for   the
partnership  has  steadily  declined, except in  periods  of  substantially
increased  commodity pricing.  Maintenance of properties and administrative
expenses for the Partnership are increasing relative to production.  As the
properties   continue   to   deplete,   maintenance   of   properties   and
administrative costs as a percentage of production are expected to continue
to increase.

<PAGE>
Liquidity - Managing General Partner

As  of  December 31, 2003, the Managing General Partner is in violation  of
several covenants pertaining to their Amended and Restated Revolving Credit
Agreement  due  June  1, 2006 and their Senior Second Lien  Secured  Credit
Agreement  due  October  15,  2008.  Due to the  covenant  violations,  the
Managing  General  Partner is in default under their Amended  and  Restated
Revolving  Credit  Agreement  and the Senior  Second  Lien  Secured  Credit
Agreement,  and all amounts due under these agreements have been classified
as  a current liability on the Managing General Partner's balance sheet  at
December 31, 2003.  The significant working capital deficit and debt  being
in default at December 31, 2003, raise substantial doubt about the Managing
General Partner's ability to continue as a going concern.

Subsequent  to  December 31, 2003, the Board of Directors of  the  Managing
General  Partner announced its decision to explore a merger,  sale  of  the
stock  or  other transaction involving the Managing General  Partner.   The
Board  has  formed a Special Committee of independent directors to  oversee
the   sales  process.   The  Special  Committee  has  retained  independent
financial  and  legal advisors to work closely with the management  of  the
Managing General Partner to implement the sales process.  There can  be  no
assurance  that a sale of the Managing General Partner will be  consummated
or what terms, if consummated, the sale will be on.

On  May  3,  2004, the Managing General Partner entered into a cash  merger
agreement  to sell all of its stock to Clayton Williams Energy,  Inc.   The
cash  merger price is being negotiated, but is expected to be approximately
$45  per  share.   The  transaction, which is subject to  approval  by  the
Managing General Partner's shareholders, is expected to close no later than
May 21, 2004.

Recent Accounting Pronouncements

The  EITF is considering two issues related to the reporting of oil and gas
mineral  rights.  Issue No. 03-O, "Whether Mineral Rights Are  Tangible  or
Intangible Assets," is whether or not mineral rights are intangible  assets
pursuant  to  SFAS  No.  141,  "Business  Combinations."  Issue  No.  03-S,
"Application of SFAS No. 142, Goodwill and Other Intangible Assets, to  Oil
and  Gas  Companies,"  is, if oil and gas drilling  rights  are  intangible
assets,  whether  those  assets  are  subject  to  the  classification  and
disclosure provisions of SFAS No. 142.  The Partnership classifies the cost
of oil and gas mineral rights as properties and equipment and believes that
this is consistent with oil and gas accounting and industry practice.   The
disclosures required by SFAS Nos. 141 and 142 would be made in the notes to
the  financial  statements. There would be no effect on  the  statement  of
income  or  cash  flows as the intangible assets related  to  oil  and  gas
mineral rights would continue to be amortized under the full cost method of
accounting.


<PAGE>
Item 3.   Quantitative and Qualitative Disclosures About Market Risk

The  Partnership  is  not a party to any derivative or embedded  derivative
instruments.

Item 4.   Controls and Procedures

Disclosure Controls and Procedures
As  of  the three months ended March 31, 2004, H.H. Wommack, III, President
and  Chief Executive Officer of the Managing General Partner, and  Bill  E.
Coggin,  Executive  Vice  President and  Chief  Financial  Officer  of  the
Managing  General Partner, evaluated the effectiveness of the Partnership's
disclosure  controls  and  procedures.  Based  on  their  evaluation,  they
believe that:

     The  disclosure  controls  and  procedures  of  the  Partnership  were
     effective in ensuring that information required to be disclosed by the
     Partnership in the reports it files or submits under the Exchange  Act
     was  recorded,  processed,  summarized and reported  within  the  time
     periods specified in the SEC's rules and forms; and

     The  disclosure  controls  and  procedures  of  the  Partnership  were
     effective  in  ensuring  that  material  information  required  to  be
     disclosed by the Partnership in the report it filed or submitted under
     the  Exchange  Act was accumulated and communicated  to  the  Managing
     General  Partner's  management,  including  its  President  and  Chief
     Executive Officer and Chief Financial Officer, as appropriate to allow
     timely decisions regarding required disclosure.

Internal Control Over Financial Reporting
There  has  not been any change in the Partnership's internal control  over
financial  reporting that occurred during the three months ended March  31,
2004  that  has materially affected, or is reasonably likely to  materially
affect, it internal control over financial reporting.

<PAGE>
                       PART II. - OTHER INFORMATION


Item 1.   Legal Proceedings

          None

Item 2.   Changes in Securities

          None

Item 3.   Defaults Upon Senior Securities

          None

Item 4.   Submission of Matter to a Vote of Security Holders

          None

Item 5.   Other Information

          None

Item 6.   Exhibits and Reports on Form 8-K

               (a)  Exhibits:

               31.1 Rule 13a-14(a)/15d-14(a) Certification
               31.2 Rule 13a-14(a)/15d-14(a) Certification
               32.1 Certification of Chief Executive Officer Pursuant to 18
U.S.C. Section 1350, as
                  adopted Pursuant to Section 906 of the Sarbanes-Oxley Act
of 2002
               32.2 Certification of Chief Financial Officer Pursuant to 18
U.S.C. Section 1350, as
                  adopted Pursuant to Section 906 of the Sarbanes-Oxley Act
of 2002

               (b)  Reports on Form 8-K:

                     No  reports on Form 8-K were filed during the  quarter
               for which this report is filed.

<PAGE>
                                SIGNATURES


Pursuant  to the requirements of the Securities Exchange Act of  1934,  the
registrant  has duly caused this report to be signed on its behalf  by  the
undersigned thereunto duly authorized.


                              SOUTHWEST ROYALTIES INSTITUTIONAL
                              INCOME FUND X-C, L.P.
                              a Delaware limited partnership


                              By:  Southwest Royalties, Inc.
                                   Managing General Partner


                              By:  /s/ Bill E. Coggin
                                   ---------------------------------------
                                   Bill E. Coggin, Vice President
                                   and Chief Financial Officer



Date:  May 14, 2004

<PAGE>

                    SECTION 302 CERTIFICATION                Exhibit 31.1


I, H.H. Wommack, III, certify that:

1.    I  have  reviewed  this quarterly report on Form  10-Q  of  Southwest
Royalties Institutional Income Fund X-C, L.P.

2.Based  on my knowledge, this report does not contain any untrue statement
  of  a  material fact or omit to state a material fact necessary  to  make
  the  statements  made,  in light of the circumstances  under  which  such
  statements  were made, not misleading with respect to the period  covered
  by this report;

3.Based  on  my  knowledge, the financial statements, and  other  financial
  information  included  in  this report, fairly present  in  all  material
  respects  the financial condition, results of operations and  cash  flows
  of the registrant as of, and for, the periods presented in this report;

4.The  registrant's other certifying officer(s) and I are  responsible  for
  establishing  and  maintaining disclosure  controls  and  procedures  (as
  defined  in  Exchange  Act  Rules 13a-15(e) and  15-15(e))  and  internal
  control  over financial reporting (as defined in Exchange Act Rules  13a-
  15(f) and 15d-15(f) for the registrant and have:

  a)Designed  such  disclosure  controls and  procedures,  or  caused  such
     disclosure   controls  and  procedures  to  be  designed   under   our
     supervision,  to  ensure  that material information  relating  to  the
     registrant, including its consolidated subsidiaries, is made known  to
     us  by others within those entities, particularly during the period in
     which this report is being prepared;

  b)Designed  such  internal control over financial  reporting,  or  caused
     such  internal  control over financial reporting to be designed  under
     our   supervision,  to  provide  reasonable  assurance  regarding  the
     reliability  of financial reporting and the preparation  of  financial
     statements for external purposes in accordance with generally accepted
     accounting principles;

  c)Evaluated  the  effectiveness of the registrant's  disclosure  controls
     and  procedures and presented in this report our conclusions about the
     effectiveness of the disclosure controls and procedures, as of the end
     of the period covered by this report based on such evaluation; and

  d)Disclosed  in  this  report  any change in  the  registrant's  internal
     control over financial reporting that occurred during the registrant's
     most recent fiscal quarter (the registrant's fourth fiscal quarter  in
     the  case  of  an annual report) that has materially affected,  or  is
     reasonably  likely  to  materially affect, the  registrant's  internal
     control over financial reporting; and

5.The  registrant's other certifying officer(s) and I have disclosed, based
  on  our  most  recent  evaluation  of  internal  control  over  financial
  reporting,  to  the  registrant's auditors and  the  audit  committee  of
  registrant's  board  of directors (or persons performing  the  equivalent
  functions):

  a)All  significant deficiencies and material weaknesses in the design  or
     operation   of  internal  controls  over  financial  reporting   which
     reasonably  likely  to  adversely affect the registrant's  ability  to
     record, process, summarize and report financial information; and

  b)Any  fraud, whether or not material, that involves management or  other
     employees  who  have  a significant role in the registrant's  internal
     controls over financial reporting.


Date:  May 14, 2004                /s/ H.H. Wommack, III
                                   H. H. Wommack, III
                                    Chairman, President and Chief Executive
Officer
                                   of Southwest Royalties, Inc., the
                                   Managing General Partner of
                                   Southwest Royalties Institutional Income
Fund X-C, L.P.



<PAGE>
                    SECTION 302 CERTIFICATION                Exhibit 31.2


I, Bill E. Coggin, certify that:

1.    I  have  reviewed  this quarterly report on Form  10-Q  of  Southwest
Royalties Institutional Income Fund X-C, L.P.

2.Based  on my knowledge, this report does not contain any untrue statement
  of  a  material fact or omit to state a material fact necessary  to  make
  the  statements  made,  in light of the circumstances  under  which  such
  statements  were made, not misleading with respect to the period  covered
  by this report;

3.Based  on  my  knowledge, the financial statements, and  other  financial
  information  included  in  this report, fairly present  in  all  material
  respects  the financial condition, results of operations and  cash  flows
  of the registrant as of, and for, the periods presented in this report;

4.The  registrant's other certifying officer(s) and I are  responsible  for
  establishing  and  maintaining disclosure  controls  and  procedures  (as
  defined  in  Exchange  Act  Rules 13a-15(e) and  15-15(e))  and  internal
  control  over financial reporting (as defined in Exchange Act Rules  13a-
  15(f) and 15d-15(f) for the registrant and have:

  a)Designed  such  disclosure  controls and  procedures,  or  caused  such
     disclosure   controls  and  procedures  to  be  designed   under   our
     supervision,  to  ensure  that material information  relating  to  the
     registrant, including its consolidated subsidiaries, is made known  to
     us  by others within those entities, particularly during the period in
     which this report is being prepared;

  b)Designed  such  internal control over financial  reporting,  or  caused
     such  internal  control over financial reporting to be designed  under
     our   supervision,  to  provide  reasonable  assurance  regarding  the
     reliability  of financial reporting and the preparation  of  financial
     statements for external purposes in accordance with generally accepted
     accounting principles;

  c)Evaluated  the  effectiveness of the registrant's  disclosure  controls
     and  procedures and presented in this report our conclusions about the
     effectiveness of the disclosure controls and procedures, as of the end
     of the period covered by this report based on such evaluation; and

  d)Disclosed  in  this  report  any change in  the  registrant's  internal
     control over financial reporting that occurred during the registrant's
     most recent fiscal quarter (the registrant's fourth fiscal quarter  in
     the  case  of  an annual report) that has materially affected,  or  is
     reasonably  likely  to  materially affect, the  registrant's  internal
     control over financial reporting; and

5.The  registrant's other certifying officer(s) and I have disclosed, based
  on  our  most  recent  evaluation  of  internal  control  over  financial
  reporting,  to  the  registrant's auditors and  the  audit  committee  of
  registrant's  board  of directors (or persons performing  the  equivalent
  functions):

  a)All  significant deficiencies and material weaknesses in the design  or
     operation   of  internal  controls  over  financial  reporting   which
     reasonably  likely  to  adversely affect the registrant's  ability  to
     record, process, summarize and report financial information; and

  b)Any  fraud, whether or not material, that involves management or  other
     employees  who  have  a significant role in the registrant's  internal
     controls over financial reporting.


Date:  May 14, 2004                /s/ Bill E. Coggin
                                   Bill E. Coggin
                                   Executive Vice President
                                   and Chief Financial Officer of
                                   Southwest Royalties, Inc., the
                                   Managing General Partner of
                                   Southwest Royalties Institutional Income
Fund X-C, L.P.


<PAGE>
           CERTIFICATION PURSUANT TO               Exhibit 32.1
                          19 U.S.C. SECTION 1350,
                          AS ADOPTED PURSUANT TO
               SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002


      In  connection  with  the  Quarterly Report  of  Southwest  Royalties
Institutional Income Fund X-C, L.P. (the "Company") on Form  10-Q  for  the
period  ending  March  31, 2004 as filed with the Securities  and  Exchange
Commission  on the date hereof (the "Report"), I, H.H. Wommack, III,  Chief
Executive Officer of the Managing General Partner of the Company,  certify,
pursuant  to 18 U.S.C.  1350, as adopted pursuant to  906 of the  Sarbanes-
Oxley Act of 2002, that:

     (1)  The Report fully complies with the requirements of section 13(a) or
       15(d) of the Securities Exchange Act of 1934; and

     (2)   The information contained in the Report fairly presents, in  all
       material respects, the financial condition
and results of operation of the
       Company.


Date:  May 14, 2004




/s/ H.H. Wommack, III
H. H. Wommack, III
Chairman, President, Director and Chief Executive Officer
  of Southwest Royalties, Inc., the
  Managing General Partner of
  Southwest Royalties Institutional Income Fund X-C, L.P.

<PAGE>
           CERTIFICATION PURSUANT TO               Exhibit 32.2
                          19 U.S.C. SECTION 1350,
                          AS ADOPTED PURSUANT TO
               SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002


    In   connection  with  the  Quarterly  Report  of  Southwest  Royalties
Institutional Income Fund X-C, L.P. (the "Company") on Form  10-Q  for  the
period  ending  March  31, 2004 as filed with the Securities  and  Exchange
Commission  on  the date hereof (the "Report"), I, Bill  E.  Coggin,  Chief
Financial Officer of the Managing General Partner of the Company,  certify,
pursuant  to 18 U.S.C.  1350, as adopted pursuant to  906 of the  Sarbanes-
Oxley Act of 2002, that:

     (1)  The Report fully complies with the requirements of section 13(a) or
       15(d) of the Securities Exchange Act of 1934; and

     (2)   The information contained in the Report fairly presents, in  all
       material respects, the financial condition
and results of operation of the
       Company.


Date:  May 14, 2004




/s/ Bill E. Coggin
Bill E. Coggin
Executive Vice President
  and Chief Financial Officer of
  Southwest Royalties, Inc., the
  Managing General Partner of
  Southwest Royalties Institutional Income Fund X-C, L.P.


<PAGE>