Concentrating Solar Power Technology (CSP) is nowadays growing mainly due to the technical and economic success of the first projects and to the stable green pricing or support mechanisms that bridges the initial gap in electricity costs (i.e. feed-in tariffs). Future growth will depend on a successful cost reduction and on a strong effort in R&D to optimize the potential for technical improvement . Testing of new materials, components and systems is still of key importance to drive research and innovation improvements to a commercial stage. Receiver manufacturers are investing in R&D in order to improve performances and reduce costs, while project developers are demanding standards to help them evaluate satisfactorily the risks and the benefits of introducing new developments in commercial power plants. The Solar Thermal Energy Department, of the National Renewable Energy Centre (CENER) and the Applied Optics Department of the Universidad de Zaragoza (UZ) have joined efforts to develop a characterization equipment able to measure as far as possible most of the receiver optical and thermal properties. In this paper the testing facility developed by CENER-UZ is described technically. The methodology for optical and thermal characterization of solar receivers for parabolic trough collectors is explained and the preliminary results are presented and discussed in detail.