The cleavage of the amide bond of formamide in dichloromethane by attack of the hydroxyl ligand in [Mo(OH)(η 3 -C 3 H 5 )(CO) 2 (N 2 C 2 H 4 )] and [Re(OH)(CO) 3 (N 2 C 2 H 4 )] complexes was theoretically investigated at the B3LYP/6-31+G(d) level (LANL2DZ for Mo and Re atoms). The effect of CH 2 Cl 2 as solvent was evaluated by the PCM-UAHF method. According to our theoretical results the more favorable mechanisms for these reactions are concerted. The energy barriers obtained by us (54.6kcalmol −1 for [Mo(OH)(η 3 -C 3 H 5 )(CO) 2 (N 2 C 2 H 4 )] and 51.9kcalmol −1 for [Re(OH)(CO) 3 (N 2 C 2 H 4 )]) are higher than those found for the neutral hydrolysis of formamide in water (about 44–46kcalmol −1 ). In contrast with water solvent, the effect of bulk CH 2 Cl 2 is quite important increasing the barriers of these two concerted processes by about 2 and 6kcalmol −1 , respectively, and making more favorable the concerted mechanism in solution in the case of the Mo complex.