Spent samples of V 2 O 5 /SiO 2 -γAl 2 O 3 catalyst used for H 2 SO 4 production were acid treated to recover vanadium. Fresh, spent, and acid treated samples were characterized by temperature-programmed techniques: TPR-H 2 , TPO-O 2 , TPD-NH 3 and, TGA-DTA in order to determine the effect of deactivating species on vanadium recovery. DRX and UV-Vis techniques were used to confirm several signals from the temperature-programmed profiles. The results suggest that vanadium sulfovanadates and oxides in treated samples strongly interact with the support making it difficult to get more than 86% vanadium recovery.