Solar thermal parabolic trough collectors can be used to provide heat for desalination, cooling and electricity generation. The set-up and some intermediate results of a measurement campaign for the evaluation of a parabolic trough collector - the Solitem PTC1800 - are presented. Optical tests of the concentrator were used to determine the intercept factor, allowing to give recommendations for optical improvements. Thermal testing up to 200 degrees C with pressurised water showed low radiative and convective losses.