Isobaric vapor-liquid equilibrium (VLE) data are reported at 101.3, 80.0 and 53.3 kPa for six binary systems of I-chlorobutane with heptane, cyclohexane and toluene, and 2-chlorobutane with the same hydrocarbons. The experimental isobaric T. x and y data were fitted to four two-parameter models namely Redlich-Kister, NRTL (alpha(12) = 1), Wilson and UNIQUAC. The maximum likelihood principle was applied to adjust the model parameters. (c) 2006 Elsevier B.V. All rights reserved.