FORM 4 Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b). Check this box to indicate that a transaction was made pursuant to a contract, instruction or written plan that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). See Instruction 10.

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP OF SECURITIES Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934 or Section 30(h) of the Investment Company Act of 1940

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1. Name and Address of Reporting Person * Ainscow Robert 2. Issuer Name and Ticker or Trading Symbol ASP Isotopes Inc. [ASPI] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director _____ 10% Owner __X__ Officer (give title below) _____ Other (specify below) Chief Operating Officer (Last) (First) (Middle) C/O ASP ISOTOPES INC., 601 PENNSYLVANIA AVENUE NW SUITE 900 3. Date of Earliest Transaction (Month/Day/Year) 09/08-05:00/2025 (Street) WASHINGTON, DC 20004 4. If Amendment, Date Original Filed (Month/Day/Year) 6. Individual or Joint/Group Filing (Check Applicable Line) _X_ Form filed by One Reporting Person ___ Form filed by More than One Reporting Person (City) (State) (Zip) Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned

1.Title of Security (Instr. 3) 2. Transaction Date (Month/Day/Year) 2A. Deemed Execution Date, if any (Month/Day/Year) 3. Transaction Code (Instr. 8) 4. Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5) 5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4) 6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4) 7. Nature of Indirect Beneficial Ownership (Instr. 4) Code V Amount (A) or (D) Price Common Stock 09/08-05:00/2025 S(1) 8,438 D $8.5263(2) 1,411,554 D Common Stock 09/09-05:00/2025 M 150,000 A $0.25 1,564,554 D Common Stock 09/09-05:00/2025 F(3) 4,396 D $8.53 1,557,158 D Common Stock 09/09-05:00/2025 M 12,000 A $2 1,569,158 D Common Stock 09/09-05:00/2025 F(3) 2,813 D $8.53 1,566,345 D Common Stock 09/09-05:00/2025 M 135,000 A $2 1,701,345 D Common Stock 09/09-05:00/2025 F(3) 31,652 D $8.53 1,669,693 D

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Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned
(e.g., puts, calls, warrants, options, convertible securities)

1. Title of Derivative Security (Instr. 3)

2. Conversion or Exercise Price of Derivative Security

3. Transaction Date (Month/Day/Year)

3A. Deemed Execution Date, if any (Month/Day/Year)

4. Transaction Code (Instr. 8)

5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4, and 5)

6. Date Exercisable and Expiration Date (Month/Day/Year)

7. Title and Amount of Underlying Securities (Instr. 3 and 4)

8. Price of Derivative Security (Instr. 5)

9. Number of Derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)

10. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 4)

11. Nature of Indirect Beneficial Ownership (Instr. 4)

Code

V

(A)

(D)

Date Exercisable

Expiration Date

Title

Amount or Number of Shares

Employee Stock Option (right to buy)

$0.25

09/09-05:00/2025

M

150,000

10/04-05:00/2024(4)

10/04-05:00/2031

Common Stock

150,000

$ 0

0

D

Employee Stock Option (right to buy)

$2

09/09-05:00/2025

M

12,000

04/04-05:00/2023(5)

04/04-05:00/2032

Common Stock

12,000

$ 0

0

D

Employee Stock Option (right to buy)

$2

09/09-05:00/2025

M

135,000

06/10-05:00/2025(6)

06/10-05:00/2032

Common Stock

135,000

$ 0

0

D

Reporting Owners

Reporting Owner Name / Address	Relationships
	Director	10% Owner	Officer	Other
Ainscow Robert C/O ASP ISOTOPES INC. 601 PENNSYLVANIA AVENUE NW SUITE 900 WASHINGTON, DC 20004			Chief Operating Officer

Signatures

/s/ Donald Ainscow, as attorney-in-fact		09/10-05:00/2025
**Signature of Reporting Person		Date

Explanation of Responses:

*	If the form is filed by more than one reporting person, see Instruction 4(b)(v).
**	Intentional misstatements or omissions of facts constitute Federal Criminal Violations. See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
(1)	Represents "sell to cover" sales effected pursuant to a Rule 10b5-1 trading plan adopted by the filing person on June 9, 2025 to cover tax withholding obligations in connection with the vesting of restricted stock awards.
(2)	The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $8.31 to $8.79, inclusive. The reporting person undertakes to provide ASP Isotopes Inc. (the "Company"), any stockholder of the Company, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in Footnote 2.
(3)	Represents shares withheld by the Company in connection with net share settlement to satisfy the exercise price associated with the reporting person's exercise of employee stock options. No shares were sold by the reporting person to satisfy the exercise price or any tax liability.
(4)	These options vested in thirty-six equal installments beginning on the last day of month after the option's grant date. The option was granted on October 4, 2021.
(5)	These options vested in a single installment 12 months after the grant date. The option was granted on April 4, 2022.
(6)	These options vested in thirty-six equal installments beginning on the last day of month after the option's grant date. The option was granted on June, 10, 2022.

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