A facile solid state reaction route was employed to synthesize the Co3O4/ZnO p-n heterostructure by grinding zinc acetate, Co3O4 and sodium hydroxide with appropriate molar ratios together at room temperature without any surfactant or template. The as-obtained samples were characterized for the surface structure, chemical state, phase structure using field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), photoluminescence spectroscopy (PL), Brunauer-Emmett-Teller (BET) analysis. The photodegradation of Rhodamine B (RhB) dye clearly revealed that the photocatalytic activity of the prepared Co3O4/ZnO p-n heterostructure was higher than that of pure ZnO nanostructure and 7% Co3O4 loaded Co3O4/ZnO photocatalyst exhibited the maximum photocatalytic activity. Under UV light it was also found to be more than five times that of pure ZnO. The photoluminescence (PL) emission spectroscopy confirmed the high separation efficiency of the photogenerated electrons-holes in the Co3O4/ZnO heterostructure which led to the high photocatalytic activity of the material. (C) 2016 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.