A series of orthorhombic photocatalysts (AgNbO 3) 1− x (NaNbO 3) x solid solutions have been synthesized by a solid-state reaction method. The composition dependence of the photophysical and photocatalytic properties of synthesized solid solutions has been investigated systematically. With an increase in the content of NaNbO 3, we found that (1) the lattice parameters decreased; (2) the Nb–O bond length in NbO 6 octahedron reduced; (3) the band gap increased; and (4) the mean particle size decreased while the Brunauer–Emmett–Teller (BET) surface area increased. Photocatalytic activities of the (AgNbO 3) 1− x (NaNbO 3) x (0⩽ x⩽0.5) samples were evaluated from gaseous 2-propanol (IPA) decomposition into acetone and CO 2 under visible-light irradiation emitted from blue-light-emitting diodes (BLEDs; light intensity: 0.01 mW cm −2). Among all the samples, the (AgNbO 3) 0.6(NaNbO 3) 0.4 sample showed the highest photocatalytic activity.