Co-3(OH)(2)(HPO4)(2)/LaTiO2N composites with a special microstructure were constructed by in-situ hydro thermally growing Co-3(OH)(2)(HPO4)(2) nano-needles on the surfaces of LaTiO2N irregular brick-like chunks. An effective heterojunction in the composites was formed based on the matched band structures and the close interfacial combination between Co-3(OH)(2)(HPO4)(2) and LaTiO2N, and thus improved the separation and transfer of photo-generated carriers. Consequently, photocatalytic O-2-evolution activity of the composites was enhanced up to 3.5 times that of LaTiO2N.