The numerical database DETHERM provides thermophysical property data, which are indispensable for construction and design of chemical apparatus, plants and processes. DETHERM contains literature values, together with bibliographical information, descriptors and abstracts. The following properties for pure compounds and for mixtures are stored: 1) phase equilibrium data, 2) vapor pressures and critical data, 3) thermodynamic properties, 4) transport properties, 5) surface tensions, 6) electrolyte data.