Vapour pressures of (benzene+1,1,2,2-tetrachloroethane (TCANE)), or (benzene+tetrachloroethene (TCENE)) at nine temperatures between 283.15 and 323.15K were measured by a static method. The reduction of the vapour pressures to obtain activity coefficients and excess molar Gibbs energies was carried out by fitting the vapour pressure data to the Redlich–Kister polynomial according to Barker's method. A comparative analysis about the thermodynamic behaviour of both systems is performed, taking into account the resonance effect in tetrachloroethene.