Graphene quantum dots (GQDs) and nitrogen -doped graphene quantum dots (N-GQDs) have been synthesized by a hydrothermal process. Optical absorption study revealed strong ultraviolet photoabsorption for both GQDs. An additional broad absorption band in the visible region has been observed for N doped GQDs. GQDs and N-GQDs both are highly luminescent and exhibit excitation dependent emission behaviors. Photoelectrochemical properties of GQD and N-GQD sensitized ZnO nanorods have been investigated in details. GQD modified nanorod photoanodes demonstrated superior photoconversion efficiency and incident photon to current conversion efficiency (IPCE) than pristine ZnO nanorods. N-GQD sensitized nanorods exhibited better photoelectrochemical properties than pristine GQD due to higher visible photoabsorption and lower interfacial resistance. (C) 2016 Elsevier B.V. All rights reserved.