We report the fabrication and characterization of ZnO-based UV photodiodes with p-NiO as an intermediate electron blocking layer (EBL). The n-ZnO and p-ZnO layers are deposited by automated spray pyrolysis technique and NiO layers by r.f.magnetron sputtering. For the realization of p-ZnO, dual acceptor method has been adopted by doping equimolar concentration of group-V elements P and N (0.75 at%)simultaneously in ZnO. The formation of p-type characteristics in ZnO is confirmed by Hall measurement and X-ray photoelectron spectroscopy (XPS)analysis. The n-ZnO is doped with Al (3 at%)in order to improve the electrical properties. The properties of sputtered NiO layers have been investigated under three different deposition temperatures of 300 degrees C, 350 degrees C and 400 degrees C. By analyzing structural and electrical properties, it is revealed that NiO deposited at 350 degrees C possess better crystallinity and electrical properties. The optimum p-ZnO and n-ZnO layers are stacked upon ITO substrates to form ZnO-based p-n junctions. The effect of addition of NiO as an electron blocking layer (EBL)between the p-n junctions is investigated by analyzing the current density-voltage (J-V)and UV photoresponse properties. The fabricated ZnO-based UV photodiodes with NiO EBL exhibits a high photoresponsivity (R)value of 5.53 A/W with external quantum efficiency (EQE)value of 1.87 x 10(3)%. (C) 2016 Elsevier B.V. All rights reserved.