Isothermal P, x, and y data were measured for twelve systems, Nine were binary chloroalkane + hydrocarbon systems, namely : 1-chlorobutane, 2-chlorobutane and 2-chloro-2-methylpropane with n-heptane, toluene and methylcyclohexane. Similar data were also measured for the binary systems 1-chlorobutane + 2-chlorobutane, 1-chlorobutane + 2-chloro-2-methylpropane and 2-chlorobutane + 2-chloro-2-methylpropane. The experimental data were correlated using the following five two-parameter models by means of the maximum likelihood method : 3-suffix Margules, van Laar, Wilson, NRTL (alpha = 1) and UNIQUAC. Vapour pressure data for 2-chlorobutane are reported.