| Cover | Aug. 23, 2021 |
| Affiliate, Collateralized Security [Line Items] | |
| Document Type | 8-K |
| Amendment Flag | false |
| Document Period End Date | Aug. 23, 2021 |
| Current Fiscal Year End Date | --12-31 |
| Entity File Number | 000-06890 |
| 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 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Entity Emerging Growth Company | false |
| Common Stock, par value | |
| Affiliate, Collateralized Security [Line Items] | |
| Title of 12(b) Security | Common Stock, par value |
| Trading Symbol | MKTY |
| Security Exchange Name | NASDAQ |
| 9.0% Series A Cumulative Perpetual Preferred Stock | |
| Affiliate, Collateralized Security [Line Items] | |
| Title of 12(b) Security | 9.0% Series A Cumulative Perpetual Preferred Stock |
| Trading Symbol | MKTYP |
| Security Exchange Name | NASDAQ |
