The heterobimetallic complexes [Y][M(N)R 2 (µ-O) 2 CrO 2 ] (where Y is either N(n-Bu) 4 + or PPh 4 + ; M is either Ru or Os; and R is an alkyl or aryl ligand) catalyze the selective oxidation of alcohols with molecular oxygen. The rate of the reaction is higher with a ruthenium-containing complex than with an analogous osmiumcontaining catalyst. The rate decreases with steric bulk in either the catalyst or substrate. Single-crystal X-ray diffraction studies of [N(n-Bu) show the chromate group coordinated to each nitrido(dialkyl)metal center through two oxo ligands. The oxidation of benzyl alcohol by [N(n-Bu) 4 ][Os(N)(CH 2 SiMe 3 ) 2 (µ-O) 2 CrO 2 ] was examinined in detail. It is first order in alcohol and substrate, and, when oxygen partial pressure is low, the rate depends directly on the O 2 partial pressure. A mechanism in which alcohol coordinates to the osmium center and is oxidized by β-hydrogen elimination is consistent with the data. [N(n-Bu) 4 ][Os(N)(CH 2 SiMe 3 ) 2 (µ-O) 2 CrO 2 ] catalyzes the oxidation of dppe with O 2 through a different pathway.