We report the nanoporous Ag2O based on the copper terephthalate metal-organic frameworks (Ag2O/MOF) photocatalyst. Ag2O/MOF nanostructure was formed via oxygen treatment of Ag/MOF nanoparticles. The resulting Ag2O/MOF photocatalysts were characterised by various techniques. Results showed that the synthesised Ag2O/MOF nanocomposite exhibited dramatic separation of photoinduced electron/hole and excellent photodegradation activity under visible light irradiation. The degradation rate of acid blue 92 using Ag2O/MOF nanocomposite is found to be higher than that using pure MOF and Ag/MOF. It was divulged that the photodegradation rate is increased by oxygen treatment of Ag in Ag/MOF structure. The possible mechanism for the enhanced photocatalytic properties of the Ag2O/MOF nanocomposite was also discussed. Similar to the mechanism proposed in the photodegradation by the other semiconductors, we propose that the photodegradation mechanism involves the generation of nonselective hydroxyl radicals concluding from the photoexcitation of the Ag2O semiconductor. All these results suggested that the catalysis occurs on the surface of nanocomposite, whose surface are covered with the Ag2O photocatalysts. The observed results on the both rate and efficiency of photodegradation are discussed in terms of (1) the surface area of synthesised MOF covered with Ag (Ag2O) and (2) separation of e (-)/h (+) pairs. Our research paves the way to design and develop highly effective and stable visible light-induced photocatalysts for the degradation of organic pollutants for water purification.