Cr3+-doped MgF2 systems are synthesised by a novel non-aqueous soft chemistry route using different Cr precursors and varying Cr loading. These systems have been characterized by X-ray powder diffraction (XRD), BET surface area, TPD of ammonia, FT-IR pyridine adsorption analysis and X-ray photoelectron spectroscopy, and tested for their catalytic activity in dismutation of CCl2F2 and CF3-CHCIF Catalysts synthesised starting from CrO3 or (CH3CO2)(7)Cr-3(OH)(2) showed better catalytic activity than those prepared with CrCl3. Fr-IR pyridine adsorption studies reveal that the catalytic activity is highly correlated with the Lewis acid strength. In TPD of NH3 catalysts prepared from CrO3 and (CH3CO2)(7)Cr-3(OH)(2), precursors showed a similar behaviour, different from that of catalysts prepared from CrCl3. (c) 2004 Elsevier B.V. All rights reserved.