Stannic oxide-titanium dioxide (SnO2-TiO2) coupled semiconductor photocatalyst loaded with polyaniline (PANI), a conducting polymer, possesses a high photocatalytic activity in oxidation of 1-octene to 1,2-epoxyoctane with aqueous hydrogen peroxide. The photocatalyst was prepared by impregnation of SnO2 and followed by attachment of PANI onto a TiO2 powder to give sample PANI-SnO2-TiO2. The electrical conductivity of the system becomes high in the presence of PANI. Enhanced photocatalytic activity was observed in the case of PANI-SnO2-TiO2 compared to PANI-TiO2, SnO2-TiO2 and TiO2. A higher photocatalytic activity in the oxidation of 1-octene on PANI-SnO2-TiO2 than SnO2-TiO2, PANI-TiO2 and TiO2 can be considered as an evidence of enhanced charge separation of PANI-SnO2-TiO2 photocatalyst as confirmed by photoluminescence spectroscopy. It suggests that photoinjected electrons are tunneled from TiO2 to SnO2 and then to PANI in order to allow wider separation of excited carriers.