Document And Entity Information - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2025	Mar. 11, 2026
Document Information [Line Items]
Document Type	10-K/A
Document Annual Report	true
Document Period End Date	Dec. 31, 2025
Document Transition Report	false
Entity File Number	001-37758
Entity Registrant Name	Moleculin Biotech, Inc.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	47-4671997
Entity Address, Address Line One	5300 Memorial Drive, Suite 950
Entity Address, City or Town	Houston
Entity Address, State or Province	TX
Entity Address, Postal Zip Code	77007
City Area Code	713
Local Phone Number	300-5160
Title of 12(b) Security	Common Stock, par value $0.001 per share
Trading Symbol	MBRX
Security Exchange Name	NASDAQ
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	false
ICFR Auditor Attestation Flag	false
Document Financial Statement Error Correction [Flag]	false
Entity Shell Company	false
Entity Public Float	$ 8.8
Entity Common Stock, Shares Outstanding (in shares)		5,336,350
Auditor Name	GRANT THORNTON LLP
Auditor Location	Fort Lauderdale, Florida
Auditor Firm ID	248
Amendment Description	Moleculin Biotech, Inc. is filing this Amendment No. 1 on Form 10-K/A, or this Amendment No. 1 to our Annual Report on Form 10-K for the fiscal year ended December 31, 2025, or the Original 10-K, originally filed with the U.S. Securities and Exchange Commission, or SEC, on March 18, 2026, or Original Filing Date, solely for the purpose of including the information required by Items 10 through 14 of Part III of Form 10-K. This information was previously omitted from the Original 10-K in reliance on General Instruction G(3) to Form 10-K, which permits the information in the above referenced items to be incorporated in the Original 10-K by reference from our definitive proxy statement so long as such proxy statement is filed no later than 120 days after our fiscal year-end. We are filing this Amendment No. 1 to include the Part III information in the Original Form 10-K because we will not file a definitive proxy statement containing such information within 120 days after the end of the fiscal year covered by the Original 10-K.
Entity Central Index Key	0001659617
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2025
Document Fiscal Period Focus	FY
Amendment Flag	true