A Bi-based oxychloride Bi3O4Cl with a layered structure as a novel efficient photocatalyst was studied in thepresent paper. The compound synthesized by a solid-state reaction method has a band gap of 2.79 eV. Thematerial possesses a fair visible-light-induced photocatalytic activity. Generally, the photocatalytic efficiencyof Bi3O4Cl for degrading methyl orange (MO) is higher than that of anatase TiO2 under UV light illumination.The dispersion of Ag over Bi3O4Cl leads to an obvious increase in the photocatalytic performance. The MOdecolorization over Bi3O4Cl is mainly initiated by a photocatalytic process. The photocatalytic activity isdiscussed in close connection with the crystal structure and the electronic structure in details.