Abstract : The Test Facility of the \Compact Linear Collider" (CLIC) at CERN, has to prove the feasibility of transporting high charged beams (20 nC) through decelerating structures at 30 GHz to create RF power. This RF power is used to supply, in the final scheme, the cavities of the main Linac. To optimise this power generation a bunch compressor has been installed in the test line. This compressor shorten the electron bunches after creation and acceleration in the RF gun. The compressed beams are then accelerated by a high gradient cavity (50 MV/m) and transported to a 30 GHz cavity. Compressed bunch length measurements showed that lengths of 0.6 mm (rms) were obtained at the entrance of 30 GHz cavity for a 10 nC beam. Compression of electron bunches of charges between 2 and 17 nC have been also measured. Emittance measurements were done to study the transverse effects of the bunch compressor on the beam. The use of the code PARMELA allowed the design and optimisation of the chicane. The simulation results have been compared to the experimental measurements.