Silver vanadate (SVO) containing SBA-15 visible-light-driven photocatalyst was synthesized using the incipient wetness impregnation procedure. The formation of reaction intermediates during the photocatalytic oxidation of gaseous toluene and the reliability test of SVO/SBA-15 were characterized by in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). The SVO/SBA-15 photocatalyst has a much higher photodegradation ability than those of P25 (nano-TiO2) and plain SVO. The sample loaded with 51 wt% SVO (51SVO/SBA-15) exhibited the best photocatalytic activity. The DRIFT spectra indicate that the main oxidation intermediate of toluene is benzaldehyde. The results of two consecutive cyclic runs and regeneration indicate that the accumulation of benzaldehyde causes an irreversible deactivation of P25, but no deactivation of 51SVO/SBA-15. DRIFTS also confirms the presence of surface hydroxyl groups and Brønsted and Lewis acids on the SVO/SBA-15 composites. The abundant surface hydroxyl groups and high intensities of Brønsted and Lewis acids are considered the main causes of the enhanced adsorption capacity, outstanding photoactivity, and long term stability of the SVO/SBA-15 composites.