Vapor-liquid equilibrium data, heat of mixing (excess enthalpies), and volumetric properties of systems are required for both the applications in design of industrial technological processes and the understanding the structure and the intermolecular interactions in the systems. On the basis of classical thermodynamics the measured experimental data combined together enable us the calculation of non-measurable thermodynamic properties significant for the technological calculations. The present volume is a compilation of experimental and derived property data on subcritical binary homogeneous (single-phase) or heterogeneous (two-phase) liquid–liquid mixtures. All the components are well-defined pure substances, which are organic nonelectrolytes and water. Only data obtained by, or derived from, direct experimental measurements are considered.The present Subvolume A reproduces in tables and graphs the numerical values for 800 binary mixtures (out of a total of 2846 systems). The remainder is published in Subvolumes B and C.