Microwave irradiation effectively accelerates cross-couplingmetathesis reactions between deactivated olefins. Reactionshave been carried out with the phosphine-free Hoveyda−Grubbs catalyst and the “second generation Grubbs' catalyst.” While there have been reports that a “microwave effect”is observed in various transformations, the accelerations weobserve are due to the efficient and rapid heating andincreased pressure in the microwave apparatus.