A large CdTe-based tomographic system has been installed two years ago on the TORE SUPRA tokamak, for a detailed investigation of the dynamics of fast electrons generated by radio-frequency waves in Fusion plasmas, as a function of time, space and energy. With 59 chords and 8 energy channels per line-of-sight, this diagnostic is the largest in the fusion community dedicated to hard X-ray studies emitted by the plasma between 20 and 200 keV. A description of the tomography as well as its performance in the aggressive environment (gamma, neutrons, time-varying magnetic field) is presented. (C) 2001 Elsevier Science B.V. All rights reserved.