Excess isobaric heat capacities of the mixtures {x cyclohexane, or benzene, or toluene + (1 - x) methylcyclohexane} and {x 2-butanone + (1 - x) methylcyclohexane or cyclohexane} were measured at 298.15 K, The mixtures {x toluene + (1 - x) cyclohexane} and {x cyclohexanone + (1 - x) methylcyclohexane, or cyclohexane, or toluene, or benzene} already reported were referred to be compared with them. The excess heat capacities of the methyl substituted molecule systems shift to positive direction from that of the non-substituted molecule systems, for the corresponding solvents. This phenomenon seems to relate to an entropy contribution due to the less molecular symmetry of the methyl-substituted molecules.