VLE for (CH3Cl + HCl) has been experimentally determined at temperatures (159.01 and 182.33) K, using a static; method. The data were used to calculate the molar excess Gibbs energy at the two temperatures. The excess molar enthalpy estimated from the G(m)(E) values for the equimolar mixture is relatively large and negative: H-m(E) = -(1011 +/- 318)J center dot mol(-1). The results have been compared with estimates from the chemical theory of solutions. (c) 2004 Published by Elsevier Ltd.