Previously unknown bis(alkoxyethynyl)-substituted silanes, germanes, and stannanes were synthesized. Pyrolysis of bis(ethoxyethynyl) -substituted silanes and germanes was studied. Depending on the reaction conditions (pyrolysis in a solvent or vacuum pyrolysis without a solvent), the process affects either one ethoxyethynyl group to give (ethoxyethynyl)silyl(-germyl)ketenes or both ethoxyethynyl groups, affording silyl- and germylbisketenes. Pyrolysis of bis(alkoxyethynyl)dimethylstannanes follows another route, resulting in 1,1-bis(alkoxy)-2,2-bis[(alkoxyethynyl)dimethylstannyl]ethenes.