Isothermal vapor-liquid equilibrium data are measured for the ternary system methanol + dimethyl carbonate (DMC) + dimethyl oxalate (DMO) and constituent binary systems at different temperatures. The activity coefficients were found to be thermodynamically consistent and were correlated by the Wilson, NRTL and UNIQUAC equations. The correlated parameters of the constituent binary systems were used to calculate the phase behavior of the ternary mixture, which showed satisfactory agreement with the experiments. (C) 2004 Elsevier B.V. All rights reserved.