Density and viscosity data of propyl formate + benzene, isopropyl benzene, isobutyl benzene, or butylbenzene have been determined at T = (303.15, 308.15, and 313.15) K. From this data, the excess volume, V(E), deviation in viscosity, Delta eta, and excess Gibbs energy of activation, Delta G*(E), have been estimated. The results of V(E) have been correlated using the semiempirical equation proposed by Hwang et al. The viscosity data have been correlated with the equation of Tamura and Kurata, Heric, and Auslander.