The predictive capability of the UNIFAC model by Fredenslund et al. (1977) using the last revised parameters of Hansen et al. (1991) was tested to describe the behavior of the binary systems of pentan-3-one + chloroalkane and 5-chloro-2-pentanone + hydrocarbon in the range of 313.15-373.15 K at low or moderate pressures. The chloroalkanes under study were 1,2-dichloroethane, 1,3-dichloropropane, 1,4-dichlorobutane, trichloromethane, 1,1,1-trichloroethane, and 1,1,2,2-tetrachloroethane; the hydrocarbons investigated were n-hexane, toluene, and ethylbenzene. The results obtained were compared with the experimental data on VLE and the excess Gibbs energy reported recently by Teodorescu et al. (1997, 1998), The best results in prediction were found for the system of pentan-3-one + 1,4-dichlorobutane with average deviation up to 0.0041 for the vapor-phase composition and up to 1.83 % in pressure. For the other systems of dichloroalkanes the deviations increase with decreasing size of chloroalkane. For the systems of trichloro- or tetrachloroalkanes the deviations are larger than for dichloroalkanes in both vapor-phase composition and pressure. For the mixtures of 5-chloro-2-pentanone + hydrocarbon the best prediction was obtained for n-hexane (up to 0.0058 in the vapor-phase composition and 5.70 % in pressure). The best description of the excess Gibbs energy is given for 5-chloro-2-pentanone + n-hexane mixture.