A series of 3V-xFe/MgF2 catalysts with different V/Fe molar ratios were prepared by a sol-gel method, and the effect of Fe promotion on the catalytic performance of gas-phase dehydrofluorination of 1,1,1,3,3-penta-fluoropropane (HFC-245fa) was investigated. It was found that proper V/Fe ratio was helpful to improve the activity. The 3V-0.5Fe/MgF2 catalyst (with a V/Fe ratio of 6/1) gave a HFC-245fa conversion of 76.6% at 320 degrees C, which was 13.4% higher than that on the 3V/MgF2 (63.2%). The synergy between V and Fe species resulted in enhanced surface acidity which accounts for the enhanced activity. The VOx and FeOx species in the fresh catalyst could be transformed to VOFx and FeF3 species during the reaction, which were regarded as the active sites. However, higher content of Fe in the catalyst resulted in the partial coverage of V species, which led to decline of surface acidity and thus the suppressed activity. Also, surface carbon deposition was responsible for the slight catalyst deactivation.