Isothermal (vapor + liquid) equilibrium data are reported for the binary mixtures containing (nitromethane or nitroethane + 1,4-dichlorobutane) at three temperatures, (343.15, 353.15, 363.15) K. The measurements were performed by means of an ebulliometer which allows sampling from both phases in equilibrium. The experimental data were correlated using the Redlich-Kister, Wilson, NRTL and UNIQUAC excess Gibbs energy models by means of maximum likelihood method, taking into account the vapour phase imperfection in terms of the second virial coefficients. Both systems are zeotropic and show positive deviations from ideal behaviour. The experimental VLE data are analysed in terms of the Modified UNIFAC (Do) model. (C) 2012 Elsevier Ltd. All rights reserved.