Extraterrestrial liquid water
The Gliese 581 planetary system contains multiple planets that may be candidates for surface water, including Gliese 581c, Gliese 581d, might be warm enough for oceans if a greenhouse effect was operating, and Gliese 581e.
Hydrogen sulfide
Hydrogen sulfide has often been detected in the interstellar medium. It also occurs in the clouds of planets in our solar system.