Isotopes of rhodium

Naturally occurring rhodium (₄₅Rh) is composed of only one stable isotope, ¹⁰³Rh. The most stable radioisotopes are ¹⁰¹Rh with a half-life of 4.07 years, ¹⁰²Rh with a half-life of 207 days, and ⁹⁹Rh with a half-life of 16.1 days. Thirty other radioisotopes have been characterized ranging from ⁸⁹Rh to ¹²²Rh - these have half-lives that are less than an hour except ¹⁰⁰Rh (20.8 hours) and ¹⁰⁵Rh (35.34 hours). There are also numerous meta states with the most stable being ^102mRh with a half-life of 3.74 years and ^101mRh with a half-life of 4.34 days.

The primary decay mode before the only stable isotope, ¹⁰³Rh, is electron capture to ruthenium isotopes, and the primary mode after is beta emission to palladium isotopes. Mass numbers 102 and 104 are capable of decay in either sense.