In order to remove dissolved organic matter such as humic acid from water, a silver orthophosphate (Ag3PO4) was newly employed as a heterogeneous photocatalyst. Here, Ag3PO4 was prepared by simple ion-exchange and precipitation methods, and the physico-chemical properties were characterized by Xray diffraction, ultraviolet-visible diffuse reflectance spectroscopy, scanning electron microscopy, particle distribution measurements and Brunauer-Emmett-Teller (BET) analysis. The degradation of humic acid was faster over Ag3PO4 catalyst than over conventional TiO2 (P-25). The total photocatalytic properties were improved by employing not an ion-exchange method but a precipitation method; humic acid degradation was performed with a removal ratio of dissolved organic carbon of 75% under visible light (lambda = 451 nm) for 2-h irradiation. (C) 2012 Elsevier Ltd. All rights reserved.