Document And Entity Information - shares	9 Months Ended
	Sep. 30, 2022	Nov. 08, 2022
Document Information [Line Items]
Entity Central Index Key	0000811212
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2022
Document Fiscal Period Focus	Q3
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2022
Document Transition Report	false
Entity File Number	333-82900
Entity Registrant Name	ThermoGenesis Holdings, Inc.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	94-3018487
Entity Address, Address Line One	2711 Citrus Road
Entity Address, City or Town	Rancho Cordova
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	95742
City Area Code	916
Local Phone Number	858-5100
Title of 12(b) Security	Common Stock, $.001 par value
Trading Symbol	THMO
Security Exchange Name	NASDAQ
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
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		45,997,792