The photocatalytic activity of TiO2 over light expanded clay aggregate granules was determined for degradation of dimethyl aminoethyl azide (DMAZ) in water with mercury lamps as UV sources. First, the catalyst was synthesized and characterized, then, the effect of various parameters on DMAZ degradation was investigated. The results showed that the photodegradation improved with increasing initial concentration of DMAZ. In addition, the DMAZ conversion grew with higher pH value and catalyst dosage. Under optimum conditions, a degradation of 54.7 % for DMAZ could be achieved. A first-order rate model presented good accordance with the experimental data.