<PAGE>
 
================================================================================

                                 UNITED STATES
                      SECURITIES AND EXCHANGE COMMISSION
                            Washington, D.C. 20549

                                   FORM 10-Q

              [X] Quarterly Report Pursuant to Section 13 or 15(d)
     of the Securities Exchange Act of 1934 for the quarterly period ended
                                 March 27, 1998

    [_] 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: 333-19495

                          RADNOR HOLDINGS CORPORATION
            (Exact name of registrant as specified in its charter)

              Delaware                                  23-2674715
     (State or other jurisdiction of                (I.R.S. Employer
     incorporation or organization)               Identification Number)
 
   Three Radnor Corporate Center, Suite 300
  100 Matsonford Road, Radnor, Pennsylvania               19087    
  (address of principal executive offices)              (Zip Code)
 
       Registrant's telephone number, including area code: 610-341-9600


     Indicate by check mark whether the 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 [_]


    The number of shares outstanding of the Registrant's common stock as of
                                 May 8, 1998:

<TABLE>
<CAPTION> 
                                                                   Number 
          Class                                                  of Shares
          -----                                                  --------- 
          <S>                                                    <C>
          Voting Common Stock; $.10 par value                       600
          Nonvoting Common Stock; $.10 par value                    245
          Class B Nonvoting Common Stock; $.01 par value          5,400
</TABLE>

================================================================================
<PAGE>
 
                        PART I - FINANCIAL INFORMATION
                                                           
Item 1.  FINANCIAL STATEMENTS
 
                 RADNOR HOLDINGS CORPORATION AND SUBSIDIARIES
                     CONDENSED CONSOLIDATED BALANCE SHEETS
                     (In thousands, except share amounts)

<TABLE>
<CAPTION>
                                                                       March 27,      December 26,
                                                                         1998             1997
                                                                      -----------     ------------
                                                                      (Unaudited)
<S>                                                                   <C>             <C>  
                           ASSETS                                     
                           ------                                     
CURRENT ASSETS                                                        
      Cash                                                             $  3,377         $  8,810            
      Accounts receivable, net                                           31,803           28,589            
      Inventories, net                                                   34,272           28,451            
      Prepaid expenses and other                                          4,771            3,520            
      Deferred tax asset                                                  1,715            1,708             
                                                                       --------         -------- 
            Total current assets                                         75,938           71,078
                                                                       --------         -------- 
PROPERTY, PLANT AND EQUIPMENT                                           180,931          176,981              
LESS - ACCUMULATED DEPRECIATION                                         (14,281)         (11,868)              
                                                                       --------         -------- 
NET PROPERTY, PLANT AND EQUIPMENT                                       166,650          165,113
                                                                       --------         -------- 
OTHER ASSETS                                                             14,481           13,627
                                                                       --------         -------- 
            Total assets                                               $257,069         $249,818
                                                                       ========         ========
            LIABILITIES AND STOCKHOLDERS' EQUITY                      
            ------------------------------------                      
CURRENT LIABILITIES                                                   
      Accounts payable                                                 $ 27,297         $ 28,565
      Accrued liabilities                                                21,136           18,151
      Current portion of long-term debt                                     172              226
                                                                       --------         -------- 
            Total current liabilities                                    48,605           46,942
                                                                       --------         -------- 
LONG-TERM DEBT, net of current portion                                  185,043          178,947
                                                                       --------         -------- 
DEFERRED TAX LIABILITY                                                    8,856            8,543
                                                                       --------         -------- 
OTHER NONCURRENT LIABILITIES                                                411              411
                                                                       --------         -------- 
COMMITMENTS AND CONTINGENCIES                                         
STOCKHOLDERS' EQUITY                                                  
      Voting and nonvoting common stock, 22,700 shares authorized,    
            6,245 shares issued and outstanding                               1                1
      Additional paid-in capital                                         19,387           19,387
      Accumulated deficit                                                (2,157)          (2,809)
      Cumulative translation adjustment                                  (3,077)          (1,604)
                                                                       --------         --------  
            Total stockholders' equity                                   14,154           14,975
                                                                       --------         -------- 
            Total liabilities and stockholders' equity                 $257,069         $249,818
                                                                       ========         ======== 
</TABLE>  

  The accompanying notes are an integral part of these condensed consolidated
                             financial statements.

                                       2
<PAGE>

                 RADNOR HOLDINGS CORPORATION AND SUBSIDIARIES
                  CONDENSED CONSOLIDATED STATEMENTS OF INCOME
                                  (Unaudited)
                                (In thousands)

<TABLE> 
<CAPTION> 
                                                              For the three months ended
                                                          -----------------------------------
                                                            March 27,            March 28,
                                                               1998                 1997
                                                          --------------       --------------
<S>                                                       <C>                  <C>  
Net sales                                                 $     71,814         $     54,028
Cost of goods sold                                              52,785               40,654
                                                          -------------        -------------

        Gross profit                                            19,029               13,374

Operating expenses:
     Distribution                                                5,173                3,988
     Selling, general and administrative                         8,526                5,489
                                                          -------------        -------------

        Income from operations                                   5,330                3,897

Other (income) expense:
     Interest                                                    4,559                2,824
     Other, net                                                   (281)                 (67)
                                                          -------------        -------------

Income from operations before
     income taxes                                                1,052                1,140

Provision for income taxes
     Current                                                        78                    -
     Deferred                                                      322                   75
                                                          -------------        -------------
                                                                   400                   75
                                                          -------------        -------------

Net income                                                $        652         $      1,065
                                                          =============        =============
</TABLE> 

  The accompanying notes are an integral part of these condensed consolidated
                             financial statements.

                                       3






<PAGE>

                 RADNOR HOLDINGS CORPORATION AND SUBSIDIARIES
                CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS
                                  (Unaudited)
                                (In thousands)

<TABLE> 
<CAPTION> 
                                                                                  For the three months ended
                                                                              ----------------------------------
                                                                                March 27,           March 28,
                                                                                   1998                1997
                                                                              -------------       -------------  
<S>                                                                           <C>                 <C> 
CASH FLOWS FROM OPERATING ACTIVITIES                                        
   Net income                                                                   $       652          $    1,065
   Adjustments to reconcile net income to cash provided by                   
     (used in) operating activities-                                         
        Depreciation                                                                  2,441               1,592
        Amortization                                                                    511                 428
        Deferred income taxes                                                           322                   -
        Changes in operating assets and liabilities                          
          Accounts receivable, net                                                   (3,562)              3,436
          Inventories                                                                (6,359)             (4,011)
          Prepaid expenses and other                                                 (1,280)                246
          Accounts payable                                                             (944)            (3,105)
          Accrued liabilities                                                         3,160               1,250
                                                                              -------------       -------------  
               Net cash provided by (used in) operating activities                   (5,059)                901
                                                                             
CASH FLOWS FROM INVESTING ACTIVITIES                                        
   Capital expenditures                                                              (4,763)             (2,842)
   Increase in other assets                                                          (1,436)               (922)
                                                                              -------------       -------------  
                                                                             
        Net cash used in investing activities                                        (6,199)             (3,764)
                                                                              -------------       -------------  
CASH FLOWS FROM FINANCING ACTIVITIES                                         
   Net borrowings on bank financed debt and                                   
    unsecured notes payable                                                           6,105               5,028
   Cash dividends                                                                         -              (2,402)
                                                                              -------------       -------------  

        Net cash provided by financing activities                                     6,105               2,626
                                                                              -------------       -------------  

EFFECTS OF EXCHANGE RATE CHANGES ON CASH                                               (280)                  -
                                                                              -------------       -------------  

NET DECREASE IN CASH                                                                 (5,433)               (237)
                                                                             
CASH, beginning of period                                                             8,810                 855
                                                                              -------------       -------------  
                                                                             
CASH, end of period                                                           $       3,377       $         618
                                                                              =============       =============
                                                                             
SUPPLEMENTAL CASH FLOW DISCLOSURES                                           
  Interest paid                                                               $         238       $          83
                                                                              =============       =============
                                                                             
  Income taxes paid                                                           $           -       $         111
                                                                              =============       =============
</TABLE> 

The accompanying notes are an integral part of these condensed consolidated
financial statements.

                                   4
<PAGE>
 
                 RADNOR HOLDINGS CORPORATION AND SUBSIDIARIES
             NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS
                                  (Unaudited)


(1)  BASIS OF PRESENTATION

     The condensed consolidated financial statements included herein have been
     prepared by Radnor Holdings Corporation and subsidiaries (collectively,
     "Radnor" or the "Company") pursuant to the rules and regulations of the
     Securities and Exchange Commission. Certain information and footnote
     disclosures normally included in consolidated financial statements prepared
     in accordance with generally accepted accounting principles have been
     condensed or omitted pursuant to such rules and regulations. In the opinion
     of the Company, the statements include all adjustments (which include only
     normal recurring adjustments) required for a fair statement of financial
     position, results of operations and cash flows for such periods. The
     results of operations for the interim periods are not necessarily
     indicative of the results for a full year.
 
 

(2)  INVENTORIES

     The components of inventories were as follows (in thousands):

<TABLE> 
<CAPTION>  
                              March 27,      December 26,   
                                1998            1997        
                             ----------      ------------    
     <S>                     <C>             <C>            
     Raw Materials            $10,117           $ 9,612        
     Work in Process            1,620             1,303     
     Finished Goods            22,535            17,536      
                              -------           -------
                              $34,272           $28,451
                              =======           ======= 
</TABLE>

(3)  INTEREST EXPENSE

     Included in interest expense is $277,000 and $140,000 of amortization of
     deferred financing costs for the three months ended March 27, 1998 and
     March 28, 1997, respectively. In addition, included in interest expense is
     debt premium amortization of $70,000 for the three months ended March 27,
     1998.

(4)  COMPREHENSIVE INCOME

     In 1998, the Company adopted Statement of Financial Accounting Standard No.
     130, Reporting Comprehensive Income, which establishes standards for the
     reporting and display of comprehensive income and its components.
     Comprehensive income is the total of net income and non-owner changes in
     equity. For the three months ended March 27, 1998 and March 28, 1997 the
     Company had comprehensive income (loss) as follows:

<TABLE>
<CAPTION>
                                                   March 27,   March 28,
                                                     1998        1997 
                                                  ----------- ----------
     <S>                                          <C>         <C>     
     Net Income                                   $    652    $  1,065
     Foreign Currency Translation Adjustment        (1,473)        (28)
                                                  --------    --------
            Comprehensive Income (Loss)           $   (821)   $  1,037
                                                  ========    ======== 
</TABLE>
     

                                       5
<PAGE>
 
(5)  SUPPLEMENTAL FINANCIAL INFORMATION

     Radnor Holdings Corporation is a holding company which has no operations or
     assets separate from its investments in subsidiaries. Radnor's $100 million
     10% Senior Notes due 2003 are guaranteed by all direct and indirect wholly
     owned subsidiaries on a full, unconditional, joint and several basis other
     then certain non-guarantor subsidiaries that individually and in the
     aggregate are inconsequential. The financial information of the non-
     guarantor subsidiaries is inconsequential. Separate financial statements of
     the guarantors are not presented because management has determined that
     they would not be material to investors.

     The Company's $60 million 10% Series B Senior Notes due 2003 are guaranteed
     by substantially all of the Company's domestic subsidiaries. The following
     represents summarized combining financial information of the holding
     company, combined guarantor subsidiaries and the combined non-guarantor
     subsidiaries as of and for the three months ended March 27, 1998 (in
     thousands):


<TABLE>
<CAPTION>
                                         Holding        Guarantor    Non-Guarantor               
                                         Company      Subsidiaries   Subsidiaries    Eliminations  Consolidated
                                         -------      ------------   ------------    ------------  ------------
     <S>                                <C>           <C>            <C>             <C>           <C>           
     Net Sales                          $      -      $  49,432      $  23,054       $    (672)    $ 71,814     
     Gross Profit                              -         12,804          6,225               -       19,029     
     Income from Operations                    -          3,520          1,810               -        5,330     
     Net Income                                -          1,081            777          (1,206)         652     
                                                                                                                
     Current Assets                        1,364         48,507         31,961          (5,894)      75,938     
     Non-Current Assets                  151,065        179,519         46,693        (196,146)     181,131     
     Current Liabilities                   5,134         28,864         16,843          (2,236)      48,605     
     Non-Current Liabilities             162,089         67,953         56,542         (92,274)     194,310      
</TABLE>

                                       6
<PAGE>
 
ITEM 2.   MANAGEMENT'S DISCUSSION AND ANALYSIS OF FINANCIAL CONDITION AND
          RESULTS OF OPERATIONS

GENERAL

     Radnor Holdings Corporation and its subsidiaries manufacture and distribute
     worldwide a variety of specialty chemical and packaging products. The
     Company's products range from value added specialty chemicals, such as
     expandable polystyrene resins, to disposable packaging sold to the
     foodservice industry. Radnor manufactures, markets and sells its products
     through five operating units comprised of twenty-two manufacturing
     locations in the U.S., Canada and Europe. The Company, through its
     predecessors, has been manufacturing foam packaging since 1961.

COMPARABILITY OF PERIODS

     Financial results for the three months ended March 27, 1998 are not fully
     comparable with the three months ended March 28, 1997 because of the
     October 1997 acquisition of the polystyrene production operations of Neste 
     Oy ("StyroChem Europe").

THREE MONTHS ENDED MARCH 27, 1998 COMPARED TO THREE MONTHS ENDED MARCH 28, 1997
 
     Net sales increased to $71.8 million for the three months ended March 27,
     1998 from $54.0 million for the same period in 1997, an increase of $17.8
     million or 33.0%. The increase was due to the acquisition of StyroChem
     Europe on October 15, 1997.

     Cost of goods sold as a percentage of net sales decreased to 73.5% for the
     three months ended March 27, 1998, from 75.2% for the same period in 1997.
     This decrease was primarily due to a decline in raw material prices
     resulting from improved market conditions.

     Gross profit increased to $19.0 million or 26.5% of net sales for the three
     months ended March 27, 1998, from $13.4 million or 24.8% of net sales for
     the same period in 1997.

     Distribution expense as a percentage of net sales decreased to 7.2% for the
     three months ended March 27, 1998, from 7.4% of net sales for the same
     period in 1997. This decrease was primarily due to increased efficiencies
     in the North American operations resulting from the realignment of shipping
     points and an increase in the percentage of full truckload shipments.

     Selling, general and administrative expenses as a percentage of net sales
     increased to 11.9% for the three months ended March 27, 1998, from 10.2% of
     net sales for the same period in 1997. This increase was due to higher
     selling and marketing expenses as well as additional administrative costs
     associated with StyroChem Europe.

     Income from operations increased to $5.3 million or 7.4% of net sales for
     the three months ended March 27, 1998, from $3.9 million or 7.2% of net
     sales for the same period in 1997.

     Interest increased to $4.6 million for the three months ended March 27,
     1998, from $2.8 million for the same period in 1997. This increase was
     primarily due to an increase in borrowings related to the acquisition of
     StyroChem Europe in October 1997.

     Income taxes were $0.4 million for the three months ended March 27, 1998,
     compared to $0.1 million for the same period in 1997. This increase relates
     to the elimination, in the prior year, of an income tax valuation allowance
     that was recorded against the Company's loss carryforward tax benefits.

                                       7
<PAGE>
 
     Net income decreased to $0.7 million or 1.0% of net sales for the three
     months ended March 27, 1998, from $1.1 million or 2.0% of net sales for the
     same period in 1997 due to the reasons described above.

LIQUIDITY AND CAPITAL RESOURCES

     During the three months ended March 27, 1998 and March 28, 1997, the
     Company's principal source of funds consisted of cash from financing
     sources. During the 1998 period, after tax cash flow of $4.0 million,
     borrowings under the Company's credit facilities of $6.1 million and a
     decrease in cash of $5.4 million were primarily used to fund capital
     expenditures of $4.8 million and a $9.0 million increase in working
     capital.

     As of March 27, 1998, the Company had $23.0 million outstanding and $12.4
     million of availability under its revolving credit agreements. The
     Company's principal uses of cash for the next several years will be working
     capital requirements and capital expenditures.

     As a holding company, Radnor Holdings Corporation is dependent upon
     dividends and other payments from its subsidiaries to generate the funds
     necessary to meet its obligations. Subject to certain limitations under
     applicable state law and the Company's credit agreements, Radnor Holdings
     Corporation is, and will continue to be, able to control its receipt of
     dividends and other payments from its subsidiaries. Management believes
     that cash generated from operations, together with available borrowings
     under the revolving credit facilities, will be sufficient to meet the
     Company's expected operating needs, planned capital expenditures and debt
     service requirements.

YEAR 2000 COMPLIANCE

     The Company is currently in the process of evaluating its information
     technology infrastructure for Year 2000 compliance. The Company does not
     expect that the cost to modify its information technology infrastructure to
     be Year 2000 compliant will be material to its financial condition or
     results of operations. The Company does not anticipate any material
     disruptions in its operations as a result of any failure by the Company to
     be in compliance. The Company does not currently have any information
     concerning the Year 2000 compliance status of its suppliers and customers.
     In the event that any of the Company's significant suppliers or customers
     does not successfully and timely achieve Year 2000 compliance, the
     Company's business operations could be adversely affected.

FORWARD LOOKING STATEMENTS

     All statements contained herein that are not historical facts are based on
     current expectations. These statements are forward looking in nature and
     involve a number of risks and uncertainties. Such risks and uncertainties
     are described in detail in the Company's Report on Form 10-K for the year
     ended December 26, 1997, Commission File No. 333-19495, to which reference
     is hereby made.

                                       8
<PAGE>
 
                          PART II  OTHER INFORMATION

Item 1.   LEGAL PROCEEDINGS

          The Company is involved in various legal actions arising in the normal
          course of business. After taking into consideration legal counsel's
          evaluation of such actions, management believes that these actions
          will not have a material effect on the Company's financial position or
          results of operations.

ITEM 6.   EXHIBITS AND REPORTS ON FORM 8-K

       (a)   Exhibits

             10.1  Second Amendment to Operating Lease dated as of February 20,
                   1998 between R/K Ventures Unit I Limited Partnership and 
                   WinCup Holdings, Inc.
             27.0  Financial Data Schedule

       (b)   Reports on Form 8-K

             There were no reports filed on Form 8-K during the three month
             period ended March 27, 1998.

                                       9
<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, its duly authorized officer and chief financial officer.


                                      RADNOR HOLDINGS CORPORATION
                                      (registrant)
                                      
                                      /s/ Michael V. Valenza
                                      -----------------------------------
Date:  May 8, 1998                    By:
                                      Michael V. Valenza
                                      Senior Vice President-Finance and Chief
                                      Financial Officer

                                       10