Ethynethiol (HCCSH) was the subject of an unsuccessful search by McGuire and co-workers, as reported in 2019. They used a number of surveys to search for rotational transitions in a variety of sources, including the high-mass star-forming regions NGC 6334I, Sgr B2(N), Orion-KL, the dark cloud Barnard 1, TMC-1, and elsewhere. The rotational constants of ethynethiol were measured by Lee and co-workers. Ethynethiol is a less stable isomer of thioketene, which was subsequently detected in 2021.

The oxygen analog of ethynethiol is ethynol (HCCOH), a compound that has evidently not been the subject of any astronomical search to date, although its rotational spectrum has been characterized theoretically by Dallas and coworkers. Turner and coworkers showed that HCCOH can be formed in ice under astrophysically relevant conditions and composition.