A detailed mechanism for the Murai reaction has not been elucidated. Experimental and computational studies give evidence for at least two different mechanisms, depending on the catalyst. For catalysts such as [Ru(H)(CO)(PR)] which are active as Ru, a combination of computational density functional studies and experimental evidence has resulted in the following proposed mechanism:
It is proposed that at high temperatures RuH(CO)(PPh) converts to an unsaturated Ru(CO)(PPh) species. The catalytic cycle is proposed to begins with coordination of the ketone followed by oxidative addition of a C-H bond.  The resulting five-coordinated metallocycle is stabilized by an agostic interaction. The C-C bond formation is the rate limiting step.