The present paper demonstrates the effect of Zn ion doping on structural, electrical and optical properties of monoclinic CuO nanoparticles prepared via microwave combustion method. The crystal structure, optical and electrical properties of synthesized CuO and Zn-doped CuO samples were characterized by X-ray diffraction study, field emission scanning electron microscopy, energy-dispersive X-ray diffraction study, UV-Visible spectroscopy, transmission electron microscopy and photoconductivity technique. The XRD values show that the crystalline size of Zn-doped CuO nanoparticles was varied with Zn concentration and also it depends on the micro-strain and dislocation density of CuO lattice. FE-SEM and TEM images indicated that the synthesized samples are of the cube and rod-like structures in nature. The band gap of CuO nanoparticles has been calculated using Tauc's plot and the result showed that the incorporation of Zn has decreased the bandgap of CuO. The I-V characterization study was performed to determine the electrical property of CuO and Zn-doped CuO films. From the results, it is observed that the photocurrent of CuO and Zn-doped CuO films is found to be greater in UV-light as compared to dark.