The gas-phase hydrofluorination of perchloroethylene (PCE) into pentafluoroethane (non ozone-depleting Freon 125) at T=330-390 degrees C and P = 0.4 MPa in the presence of a chromium-magnesium catalyst has been studied. A hydrofluorination scheme including main product and by-products formation routes is deduced from the observed dependences of particular products selectivity. The kinetic model of the PCE hydrofluorination has been developed. The rate parameters and the activation energy of the reactions were determined. The model satisfactorily describes the experimental data in the temperature range 330-390 degrees C. (C) 2011 Elsevier B.V. All rights reserved.