The photolysis of RhCH3(ttp) and RhCH3(tmp) (ttp = 5,10,15,20-tetratolylporphyrin, tmp = 5,10,15,20-tetramesitylporphyrin) was studied in methanol at ambient temperature: the quantum yields for photolysis were determined to be 0.51 and 0.54, respectively, and the Rh-C bond dissociation energies (227 and 219 kJ mol(-1), respectively) were measured by photoacoustic calorimetry, which were larger than those of Co-C bond.