Accurate thermophysical property data mainly for materials relevant for process and energy engineering over a wide range of thermodynamic states are measured by optical and conventional methods. A certain focus lies on the measurement of transport properties including mass diffusion coefficients, thermal diffusivity, thermal conductivity, and viscosity. Equilibrium properties accessible with the instrumentation available at AOT-TP are density, interfacial tension, speed of sound and sound attenuation, refractive index, and wetting parameters such as contact angles. In addition, the determination of the hydrodynamic size of different kinds of small particles (e.g., solid nanoparticles or droplets in nano- or microemulsions) in heterogeneous systems is possible via the measurement of their translational diffusion coefficient. Obtained data are analyzed to improve the understanding of structure-property relationships.