Excess molar heat capacities for binary mixtures of isomeric xylenes have been measured in the temperature range 303.65-321.65 K using a C-80 calorimeter. C(p,m)E is negative for o-xylene + m-xylene, o-xylene + p-xylene, but positive for the system m-xylene + p-xylene. Our extrapolated values at 298.15 K compare well with those reported by Fortier and Benson [Fortier, J.L. and Benson, G.C., 1980. J. Chem. Eng. Data, 25 : 47]. The results have been compared with Flory’s theory of mixtures.