Isobaric vapor-liquid equilibrium (VLE) measurements for mixtures containing tetrahydrofuran, tetrahydropyran, 1,3-dioxolane, or 1,4-dioxane and 1-chloropentane at 40.0 and 101.3 kPa are reported. Activity coefficients were calculated from experimental data and correlated with Wilson, NRTL, and UNIQUAC equations. The VLE measurements have been found to be thermodynamically consistent according to van Ness test. Using these VLE results the UNIFAC parameters between the CCI and c-CH2O groups were recalculated, and the results obtained with the new parameters can be considered to be satisfactory.