The purpose of this study was removal of ammonia by a new photocatalytic process from synthetic wastewater under UV irradiation. TiO₂ was used as the photocatalyst and immobilized on perlite granules as a supporter. The prepared catalysts were characterized by SEM and FTIR analysis showed that TiO₂/perlite catalyst has mesoporous structures and uniform coating of TiO₂ on support. Also, the optimum efficiency of photocatalytical degradation of ammonia was obtained at pH 11 for UV intensity irradiation with 125 W lamp. About 68% degradation of ammonia in wastewater was achieved after 180 min of irradiation by using the optimized reaction conditions.