Cover - shares	6 Months Ended
	Jun. 30, 2021	Aug. 09, 2021
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Quarterly Report	true
Document Transition Report	false
Document Period End Date	Jun. 30, 2021
Document Fiscal Period Focus	Q2
Document Fiscal Year Focus	2021
Current Fiscal Year End Date	--12-31
Entity File Number	001-40261
Entity Registrant Name	MECHANICAL TECHNOLOGY INC
Entity Central Index Key	0000064463
Entity Tax Identification Number	14-1462255
Entity Incorporation, State or Country Code	NV
Entity Address, Address Line One	325 Washington Avenue Extension
Entity Address, City or Town	Albany
Entity Address, State or Province	NY
Entity Address, Postal Zip Code	12205
City Area Code	518
Local Phone Number	218-2550
Title of 12(b) Security	Common Stock ($0.001 par value)
Trading Symbol	MKTY
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		12,699,670