have been discovered. Of these radioisotopes, the most stable are ¹⁰⁶Ru with a half-life of 371.8 days, ¹⁰³Ru with a half-life of 39.245 days and ⁹⁷Ru with a half-life of 2.837 days.

Fifteen other radioisotopes have been characterized ranging from ⁸⁵Ru to ¹²⁵Ru. Most of these have half-lives that are less than five minutes; the exceptions are ⁹⁴Ru (51.8 minutes), ⁹⁵Ru (1.607 hours),