The specific conductivity kappa of LiAsF6 solutions in equimolar acetonitrile + ethylene carbonate and ethylene carbonate + propylene carbonate mixtures was determined at 25-degrees-C. The values of the density d, dynamic viscosity coefficient eta and dielectric constant D of pure equimolar mixtures of acetonitrile (AN) with ethylene carbonate (EC) and of EC with propylene carbonate (PC) were measured at 25-degrees-C. The results for the dilute solutions were analysed using the Fuoss-Justice conductivity equation with Chen’s correction (FJCHEN equation). The limiting molar conductivity LAMBDA0, the ion pair association constant K(A), the distance parameter R, the degree of dissociation gamma and the mean activity coefficient f+/- were calculated. The conductivity of the concentrated solutions was analysed using the semi-empirical Casteel-Amis equation. The equation parameters c(max), kappa(max), a and b were evaluated. The isotherms of the vapour pressure p of the AN + EC mixtures were measured at 40-degrees-C and 60-degrees-C. The activity coefficients f1 and f2 of the first and second components, the excess Gibbs energy G(E) and the excess enthalpy H(E) were evaluated from the experimental data. The minimized energies of the solvent molecules were calculated using the ALCHEMY program.