[en] Decarbonylation reactions of M(CO)⁶ and M(MeCN)³(CO)³ (M=Mo, W) with tris-(tri-phenylphosphine)chlororhodium (1) in acetonitrile are studied. At 80 deg initial rhodium complex, interacting with M(CO)⁶, quantitatively transforms into Rh(PPh³)²COCl in 5 (Mo) and 10(W) min. Reactions proceed by means of sequential transfer of carbonyl groups on rhodium: coordination vacancies formed are filled with MeCN and PPh³ molecules. Complexes containing PPh³ are not practically subjected to further decarbonylation. Among M(CO)⁶ decarbonylation products cis-tetracarbonyl, cis-dicarbonyl complexes are present, i.e. reactions of carbonyl group splitting off are stereospecific. Decarbonylation of Mo(MeCN)³(CO)³ results in the formation of Mo(PPh³)²(MeCN)²x(CO)²