Exhibit 10.5


 


November
2, 2021


 


BTIG,
LLC

65 E 55th Street

New York, NY 10022


 


Re:
Initial Public Offering


 


Ladies
and Gentlemen:


 


This
letter (this “Letter Agreement”) is being delivered to you in accordance with the Underwriting Agreement
(the “Underwriting Agreement”) entered into by and among Onyx Acquisition Co. I, a Cayman Islands exempted
company (the “Company”), and BTIG, LLC, as representative (the
“Representative”) of the several underwriters named therein (the
“Underwriters”), relating to an underwritten initial public offering (the “Public
Offering”) of 26,450,000 of the Company’s units (including 3,450,000 units that may be purchased pursuant to the
Underwriters’ option to purchase additional units, the “Units”), each comprised of one of the
Company’s Class A ordinary shares, par value $0.0001 per share (the “Ordinary Shares”), and one-half
of one redeemable warrant (each whole warrant, a “Warrant”). Each Warrant entitles the holder thereof to
purchase one Ordinary Share at a price of $11.50 per share, subject to adjustment. The Units will be sold in the Public Offering
pursuant to a registration statement on Form S-1 and a prospectus (the “Prospectus”) filed by the Company
with the U.S. Securities and Exchange Commission (the “Commission”). Certain capitalized terms used herein
are defined in paragraph 1 hereof.


 


In order to induce the Company and the Underwriters to enter into the Underwriting
Agreement and to proceed with the Public Offering and for other good and valuable consideration, the receipt and sufficiency of
which are hereby acknowledged, Onyx Acquisition Sponsor Co. LLC (the “Sponsor”) and each of the
undersigned (each, an “Insider” and, collectively, the “Insiders”) hereby agree
with the Company as follows:


 


1.
Definitions. As used herein, (i) “Business Combination” shall mean a merger, share exchange, asset acquisition,
share purchase, reorganization or similar business combination with one or more businesses or entities; (ii) “Founder Shares”
shall mean the 6,612,500 Class B ordinary shares (up to 862,500 of which are subject to forfeiture depending on the extent to which the
Underwriters’ option to purchase additional units is exercised) of the Company, par value $0.0001 per share, outstanding prior
to the consummation of the Public Offering; (iii) “Private Placement Warrants” shall mean the warrants to purchase
Ordinary Shares of the Company that will be acquired by the Sponsor for an aggregate purchase price of $10,350,000 (or up to $11,040,000
if the Underwriters exercise their option to purchase additional units in full), or $1.00 per Warrant, in a private placement that shall
close simultaneously with the consummation of the Public Offering (including Ordinary Shares issuable upon conversion thereof); (iv)
“Public Shareholders” shall mean the holders of Ordinary Shares included in the Units issued in the Public
Offering; (v) “Public Shares” shall mean the Ordinary Shares included in the Units issued in the Public Offering;
(vi) “Trust Account” shall mean the trust account into which the net proceeds of the Public Offering and certain
proceeds from the sale of the Private Placement Warrants shall be deposited; (vii) “Transfer” shall mean the
(a) sale of, offer to sell, contract or agreement to sell, hypothecate, pledge, grant of any option to purchase or otherwise dispose
of or agreement to dispose of, directly or indirectly, or establishment or increase of a put equivalent position or liquidation with
respect to or decrease of a call equivalent position within the meaning of Section 16 of the Securities Exchange Act of 1934, as amended,
and the rules and regulations of the Commission promulgated thereunder with respect to, any security, (b) entry into any swap or other
arrangement that transfers to another, in whole or in part, any of the economic consequences of ownership of any security, whether any
such transaction is to be settled by delivery of such securities, in cash or otherwise, or (c) public announcement of any intention to
effect any transaction specified in clause (a) or (b); and (viii) “Charter” shall mean the Company’s
Amended and Restated Memorandum and Articles of Association, as the same may be amended from time to time.


 






     


     


    

 


2. Representations
and Warranties.


 


(a)
The Sponsor and each Insider, with respect to itself, herself or himself, represent and warrant to the Company that it, she or he
has the full right and power, without violating any agreement to which it, she or he is bound (including, without limitation, any
non-competition or non-solicitation agreement with any employer or former employer), to enter into this Letter Agreement, as
applicable, and to serve as an officer of the Company and/or a director on the Company’s Board of Directors (the
“Board”), as applicable, and each Insider hereby consents to being named in the Prospectus, road show and
any other materials as an officer and/or director of the Company, as applicable.


 


(b)
Each Insider represents and warrants, with respect to herself or himself, that such Insider’s biographical information
furnished to the Company (including any such information included in the Prospectus) is true and accurate in all material respects
and does not omit any material information with respect to such Insider’s background. The Sponsor and each Insider’s
questionnaire furnished to the Company is true and accurate in all material respects. Each Insider represents and warrants that such
Insider is not subject to or a respondent in any legal action for, any injunction, cease-and-desist order or order or stipulation to
desist or refrain from any act or practice relating to the offering of securities in any jurisdiction; such Insider has never been
convicted of, or pleaded guilty to, any crime (i) involving fraud, (ii) relating to any financial transaction or handling of funds
of another person, or (iii) pertaining to any dealings in any securities and such Insider is not currently a defendant in any such
criminal proceeding; and such Insider has never been suspended or expelled from membership in any securities or commodities exchange
or association or had a securities or commodities license or registration denied, suspended or revoked.


 


3. Business
Combination Vote. It is acknowledged and agreed that the Company shall not enter into a definitive agreement regarding a
proposed Business Combination without the prior consent of the Sponsor. The Sponsor and each Insider, with respect to itself or
herself or himself, agrees that if the Company seeks shareholder approval of a proposed initial Business Combination, then in
connection with such proposed initial Business Combination, it, she or he, as applicable, shall vote all Founder Shares and any
Public Shares held by it, her or him, as applicable, in favor of such proposed initial Business Combination (including any proposals
recommended by the Board in connection with such Business Combination) and not redeem any Public Shares held by it, her or him, as
applicable, in connection with such shareholder approval.


 






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4. Failure
to Consummate a Business Combination; Trust Account Waiver.


 


(a)
The Sponsor and each Insider hereby agree, with respect to itself, herself or himself, that in the event that the Company fails to
consummate its initial Business Combination within the time period set forth in the Charter, the Sponsor and each Insider shall take
all reasonable steps to cause the Company to (i) cease all operations except for the purpose of winding up; (ii) as promptly as
reasonably possible but not more than 10 business days thereafter, redeem 100% of the Public Shares, at a per-share price, payable
in cash, equal to the aggregate amount then on deposit in the Trust Account, including interest earned on the funds held in the
Trust Account and not previously released to the Company to pay income taxes (less up to $100,000 of interest to pay dissolution
expenses), divided by the number of then-outstanding Public Shares, which redemption will completely extinguish Public
Shareholders’ rights as shareholders (including the right to receive further liquidation distributions, if any); and (iii) as
promptly as reasonably possible following such redemption, subject to the approval of the Company’s remaining shareholders and
the Board, liquidate and dissolve, subject in the case of clauses (ii) and (iii) to the Company’s obligations under Cayman
Islands law to provide for claims of creditors and in all cases subject to the other requirements of applicable law. The Sponsor and
each Insider agree not to propose any amendment to the Charter (i) that would modify the substance or timing of the Company’s
obligation to provide holders of the Public Shares the right to have their shares redeemed in connection with an initial Business
Combination or to redeem 100% of the Public Shares if the Company does not complete an initial Business Combination within the
required time period set forth in the Charter or (ii) with respect to any other provision relating to the rights of holders of
Public Shares or pre-initial Business Combination activity unless the Company provides its Public Shareholders with the opportunity
to redeem their Public Shares upon approval of any such amendment at a per-share price, payable in cash, equal to the aggregate
amount then on deposit in the Trust Account, including interest earned on the funds held in the Trust Account and not previously
released to the Company to pay taxes, if any, divided by the number of then-outstanding Public Shares.


 


(b)
The Sponsor and each Insider, with respect to itself, herself or himself, acknowledges that it, she or he has no right, title,
interest or claim of any kind in or to any monies held in the Trust Account or any other asset of the Company as a result of any
liquidation of the Company with respect to the Founder Shares held by it, her or him, if any. The Sponsor and each of the Insiders
hereby further waive, with respect to any Founder Shares and Public Shares held by it, her or him, as applicable, any redemption
rights it, she or he may have in connection with (a) the consummation of a Business Combination, including, without limitation, any
such rights available in the context of a shareholder vote to approve such Business Combination and (b) a shareholder vote to
approve an amendment to the Charter (i) that would modify the substance or timing of the Company’s obligation to provide
holders of the Public Shares the right to have their shares redeemed in connection with an initial Business Combination or to redeem
100% of the Public Shares if the Company has not consummated an initial Business Combination within the time period set forth in the
Charter or (ii) with respect to any other provision relating to the rights of holders of Public Shares or pre-initial Business
Combination activity (although the Sponsor and the Insiders shall be entitled to liquidation rights with respect to any Public
Shares they hold if the Company fails to consummate a Business Combination within the required time period set forth in the
Charter).


 






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(c)
Each of the undersigned acknowledges and agrees that prior to entering into a definitive agreement for a Business Combination with a
target business that is affiliated with the undersigned or any other Insiders of the Company or their respective affiliates, the
Company must obtain an opinion from an independent investment banking firm or an independent accounting firm that such Business
Combination is fair to the Company from a financial point of view.


 


5. Lock-up;
Transfer Restrictions.


 


(a)
The Sponsor and the Insiders agree that they shall not Transfer any Founder Shares (the “Founder Shares
Lock-up”) until the earliest of (A) one year after the completion of an initial Business Combination and (B)
subsequent to an initial Business Combination, (i) if the closing price of the Ordinary Shares equals or exceeds $12.00 per share
(as adjusted for share sub-divisions, share capitalizations, share consolidations, reorganizations, recapitalizations and the like)
for any 20 trading days within a 30-trading day period commencing at least 150 days after the Company’s initial Business
Combination or (ii) the date on which the Company completes a liquidation, merger, share exchange or other similar transaction that
results in all of the Company’s shareholders having the right to exchange their Ordinary Shares for cash, securities or other
property (the “Founder Shares Lock-up Period”).


 


(b)
The Sponsor and each Insider agree that they shall not effectuate any Transfer of Private Placement Warrants or Ordinary Shares
underlying such warrants until 30 days after the completion of an initial Business Combination.


 


(c)
Notwithstanding the provisions set forth in paragraphs 5(a) and (b), Transfers of the Founder Shares, Private
Placement Warrants and Ordinary Shares underlying the Private Placement Warrants are permitted (a) to the Company’s officers
or directors, any affiliate or family member of any of the Company’s officers or directors, any members or partners of the
Sponsor or their affiliates, any affiliates of the Sponsor, or any employees of such affiliates; (b) in the case of an individual,
by gift to a member of one of the individual’s immediate family or to a trust, the beneficiary of which is a member of the
individual’s immediate family, an affiliate of such person or to a charitable organization; (c) in the case of an individual,
by virtue of laws of descent and distribution upon death of the individual; (d) in the case of an individual, pursuant to a
qualified domestic relations order; (e) by private sales or transfers made in connection with any forward purchase agreement or
similar arrangement or in connection with the consummation of a Business Combination at prices no greater than the price at which
the Founder Shares, Private Placement Warrants or Ordinary Shares, as applicable, were originally purchased; (f) by virtue of the
Sponsor’s organizational documents upon liquidation or dissolution of the Sponsor; (g) to the Company for no value for
cancellation in connection with the consummation of an initial Business Combination, (h) in the event of the Company’s
liquidation prior to the completion of a Business Combination; or (i) in the event of completion of a liquidation, merger, share
exchange or other similar transaction which results in all of the Company’s Public Shareholders having the right to exchange
their Ordinary Shares for cash, securities or other property subsequent to the completion of an initial Business Combination; provided, however,
that in the case of clauses (a) through (f) these permitted transferees must enter into a written agreement agreeing to be bound by
these transfer restrictions.


 






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(d)
During the period commencing on the effective date of the Underwriting Agreement and ending 180 days after such date, the Sponsor
and each Insider shall not, without the prior written consent of the Representative, Transfer any Units, Ordinary Shares, Warrants
or any other securities convertible into, or exercisable or exchangeable for, Ordinary Shares held by it, her or him, as applicable.
Each of the Insiders and the Sponsor acknowledges and agrees that, prior to the effective date of any release or waiver, of the
restrictions set forth in this paragraph 5, the Company shall announce the impending release or waiver by press release
through a major news service at least two business days before the effective date of the release or waiver. Any release or waiver
granted shall only be effective two business days after the publication date of such press release. The provisions of this paragraph
will not apply to any Transfer permitted under paragraph 5(c) hereof or if the release or waiver is effected solely to permit
a Transfer not for consideration and the transferee has agreed in writing to be bound by the same terms described in this Letter
Agreement to the extent and for the duration that such terms remain in effect at the time of the Transfer.


 


6. Remedies.
The Sponsor and each of the Insiders hereby agree and acknowledge that (i) each of the Underwriters and the Company would be
irreparably injured in the event of a breach by the Sponsor or such Insider of its, her or his obligations, as applicable under paragraphs
3, 4, 5, 7, 10 and 11, (ii) monetary damages may not be an adequate remedy for such breach
and (iii) the non-breaching party shall be entitled to injunctive relief, in addition to any other remedy that such party may have
in law or in equity, in the event of such breach.


 


7. Payments
by the Company. Except as disclosed in the Prospectus, neither the Sponsor nor any affiliate of the Sponsor nor any director or
officer of the Company nor any affiliate of the directors and officers shall receive from the Company any finder’s fee,
reimbursement, consulting fee, monies in respect of any payment of a loan or other compensation prior to, or in connection with any
services rendered in order to effectuate the consummation of the Company’s initial Business Combination (regardless of the
type of transaction that it is).


 


8. Director
and Officer Liability Insurance. The Company will maintain an insurance policy or policies providing directors’ and
officers’ liability insurance, and the Insiders shall be covered by such policy or policies, in accordance with its or their
terms, to the maximum extent of the coverage available for any of the Company’s directors or officers.


 


9. Termination.
This Letter Agreement shall terminate on the earlier of (i) the expiration of the Founder Shares Lock-up Period and (ii) the
liquidation of the Company; provided, however, that paragraph 10 of this Letter Agreement shall survive such
liquidation.


 






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10. Indemnification.
In the event of the liquidation of the Trust Account upon the failure of the Company to consummate its initial Business Combination
within the time period set forth in the Charter, the Sponsor (the “Indemnitor”) agrees to indemnify and
hold harmless the Company against any and all loss, liability, claim, damage and expense whatsoever (including, but not limited to,
any and all legal or other expenses reasonably incurred in investigating, preparing or defending against any litigation, whether
pending or threatened) to which the Company may become subject as a result of any claim by (i) any third party for services rendered
or products sold to the Company (except for the Company’s independent registered public accounting firm) or (ii) any
prospective target business with which the Company has discussed entering into a transaction agreement (a
“Target”); provided, however, that such indemnification of the Company by the Indemnitor (x)
shall apply only to the extent necessary to ensure that such claims by a third party for services rendered or products sold to the
Company or a Target do not reduce the amount of funds in the Trust Account to below the lesser of (i) $10.20 per Public Share and
(ii) the actual amount per Public Share held in the Trust Account as of the date of the liquidation of the Trust Account if less
than $10.20 per Public Share due to reductions in the value of the trust assets, in each case net of interest that may be withdrawn
to pay the Company’s tax obligations, (y) shall not apply to any claims by a third party or Target who executed a waiver of
any and all rights to the monies held in the Trust Account (whether or not such waiver is enforceable) and (z) shall not apply to
any claims under the Company’s indemnity of the Underwriters against certain liabilities, including liabilities under the
Securities Act of 1933, as amended. The Indemnitor shall have the right to defend against any such claim with counsel of its choice
reasonably satisfactory to the Company if, within 15 days following written receipt of notice of the claim to the Indemnitor, the
Indemnitor notifies the Company in writing that it shall undertake such defense.


 


11. Forfeiture
of Founder Shares. To the extent that the Underwriters do not exercise their option to purchase additional Units within 45 days
from the date of the Prospectus in full (as further described in the Prospectus), the Sponsor agrees to automatically surrender to
the Company for no consideration, for cancellation at no cost, an aggregate number of Founder Shares so that the number of Founder
Shares will equal an aggregate of 20% of the sum of the total number of Ordinary Shares and Founder Shares outstanding at such time.
The Sponsor and Insiders further agree that to the extent that the size of the Public Offering is increased or decreased, the
Company will effect a share capitalization or a share surrender or redemption or other appropriate mechanism, as applicable, with
respect to the Founder Shares immediately prior to the consummation of the Public Offering in such amount as to maintain the number
of Founder Shares, on an as-converted basis, at 20% of the sum of the total number of Ordinary Shares and Founder Shares outstanding
at such time.


 


12. Entire
Agreement. This Letter Agreement constitutes the entire agreement and understanding of the parties hereto in respect of the
subject matter hereof and supersedes all prior understandings, agreements, or representations by or among the parties hereto,
written or oral, to the extent they relate in any way to the subject matter hereof or the transactions contemplated hereby. This
Letter Agreement may not be changed, amended, modified or waived (other than to correct a typographical error) as to any particular
provision, except by a written instrument executed by all parties hereto.


 






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13. Assignment.
No party hereto may assign either this Letter Agreement or any of its rights, interests, or obligations hereunder without the prior
written consent of the other parties. Any purported assignment in violation of this paragraph shall be void and ineffectual and
shall not operate to transfer or assign any interest or title to the purported assignee. This Letter Agreement shall be binding on
the Sponsor, each of the Insiders and each of their respective successors, heirs, personal representatives and assigns and permitted
transferees.


 


14. Counterparts.
This Agreement may be executed in multiple counterparts (including facsimile or PDF counterparts), each of which shall be deemed an
original, and all of which together shall constitute the same instrument, but only one of which need be produced. Signatures to this
Letter Agreement transmitted via facsimile or e-mail shall be valid and effective to bind the party so signing (including any
electronic signature covered by the U.S. federal ESIGN Act of 2000, Uniform Electronic Transactions Act, the Electronic Signatures
and Records Act or other applicable law, e.g., www.docusign.com).


 


15. Effect
of Headings. The paragraph headings herein are for convenience only and are not part of this Letter Agreement and shall not
affect the interpretation thereof.


 


16. Severability.
This Letter Agreement shall be deemed severable, and the invalidity or unenforceability of any term or provision hereof shall not
affect the validity or enforceability of this Letter Agreement or of any other term or provision hereof. Furthermore, in lieu of any
such invalid or unenforceable term or provision, the parties hereto intend that there shall be added as a part of this Letter
Agreement a provision as similar in terms to such invalid or unenforceable provision as may be possible and be valid and
enforceable.


 


17. Governing
Law. This Letter Agreement shall be governed by and construed and enforced in accordance with the laws of the State of New York,
without giving effect to conflicts of law principles that would result in the application of the substantive laws of another
jurisdiction. The parties hereto (i) all agree that any action, proceeding, claim or dispute arising out of, or relating in any
way to, this Letter Agreement shall be brought and enforced only in the Court of Chancery of the State of Delaware, and irrevocably
submit to such jurisdiction and venue, which jurisdiction and venue shall be exclusive, and (ii) waive any objection to such
exclusive jurisdiction and venue or that such courts represent an inconvenient forum.


 


18. Notices.
Any notice, consent or request to be given in connection with any of the terms or provisions of this Letter Agreement shall be in
writing and shall be sent by express mail or similar private courier service, by certified mail (return receipt requested), by hand
delivery, facsimile or electronic transmission.


 


 


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	 	Sincerely,
	 	 	 
	 	ONYX ACQUISITION SPONSOR CO. LLC
	 	 	 
	 	By:	/s/ Michael Stern
	 	Name:	Michael Stern
	 	Title:	Manager
	 	 	 
	 	By:	/s/ Michael Stern
	 	 	Michael Stern
	 	 	 
	 	By:	/s/ Benjamin Lerner
	 	 	Benjamin Lerner
	 	 	 
	 	By:	/s/ Matthew Vodola
	 	 	Matthew Vodola
	 	 
	 	By:	/s/ Serena Rakhlin
	 	 	Serena Rakhlin
	 	 
	 	By:	/s/ Ana Soban Fernandes Kertesz
	 	 	Ana Soban Fernandes Kertesz
	 	 
	 	By:	/s/ Michael Lehmann
	 	 	Michael Lehmann
	 	 	 
	 	By:	/s/ Edmar Prado Lopes Neto
	 	 	Edmar Prado Lopes Neto



 


 


[Signature
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	 	Acknowledged and Agreed:
	 	 
	 	ONYX ACQUISITION CO. I
	 	 
	 	By:	/s/ Michael Stern
	 	Name:	Michael Stern
	 	Title:	Director, Chairman and Chief Executive Officer


 


 


[Signature
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