Photocatalytic degradation of ammonia on supported TiO2 nanoparticles was investigated. The TiO2 nanoparticles used as photocatalyst were coated on light expanded clay aggregate granules (LECA), which is a porous and light weight support. Photocatalytic reaction activity of prepared catalyst was determined by ammonia degradation from water synthetically polluted with ammonia. Experiment results showed significantly high photocatalytic activity for the immobilized catalysts. The ammonia was removed more than 85% within 300 min of the process with optimum calcinations temperature 550 ℃ and pH 11. Kinetics of the photocatalytic reaction followed a pseudo-first order model. XRF, XRD and SEM analyses revealed a rather uniform coating of TiO2 on the support. By using floated TiO2/LECA as a photocatalyst in aqueous solution of NH3, the ammonia was photodegraded into N2 and H2 gases, while NO2- and NO3- were formed at very low concentrations.