Reactions of rhodium atoms with dioxygen molecules in solid argon have been investigated using matrix isolation infrared absorption spectroscopy. The rhodium-dioxygen complexes, Rh(eta(2)-O-2), Rh(eta(2)-O-2)(2), and Rh(eta(2)-O-2)(2)(eta(1)-OO), are produced spontaneously on annealing. The Rh(eta(2)-O-2) complex rearranges to the inserted RhO2 molecule under visible light irradiation. Experiments doped with xenon in argon show that the rhodium-dioxygen complexes are coordinated by one or two noble gas atoms in solid noble gas matrixes. Hence, the Rh(eta(2)-O-2), Rh(eta(2)-O-2)(2), and Rh(eta(2)-O-2)(2)(eta(1)-OO) molecules trapped in solid noble gas matrixes should be regarded as the Rh(eta(2)-O-2)(Ng)(2), Rh(eta(2)-O-2)(2)(Ng)(2), and Rh(eta(2)-O-2)(2)(eta(1)-OO)(Ng) (Ng = Ar or Xe) complexes. The product absorptions are identified on the basis of isotopic substitution and density functional theory calculations.