The ability of ruthenium to exist in multiple oxidation states is an important property of this rare element and plays an important role in its applications. Ruthenium readily forms coordination complexes, which have applications in various fields such as medicine, catalysis, biology, nanoscience, redox and photosensitive materials. In the biomedical field, Ru is used for diagnostic and therapeutic purposes.

In the electronics industry, most are used for chip resistors and electrical contacts. Ruthenium oxide is used in the chemical industry to coat the anodes of electrochemical cells for the production of chlorine gas. Ruthenium is also used in catalysts for the production of ammonia and acetic acid. Ruthenium compounds are used in solar cells to convert light energy into electricity.
Ruthenium is one of the most effective hardeners for platinum and palladium, and alloys with these metals to form electrical contacts for extremely high wear resistance. It is used as an alloy with platinum in some jewelry.