PVP-capped Zn(1-x)NixS (x=0.001, 0.005, 0.01, 0.03, 0.05 and 0.1) nanoparticles have been synthesized using chemical precipitation route, in aqueous media, at room temperature. The synthesized nanoparticles have been irradiated by UV light for 24 h so as to study the effect on their structural and optical properties. The nanoparticles have been characterized through XRD and HRTEM to study the crystal structure and size. Characterization was also carried out through FTIR spectroscopy to reveal the presence of PVP and the effect of UV irradiation on the surface chemistry of the synthesized nanoparticles. The optical properties have been studied through UV-vis absorption spectroscopy and room temperature photoluminescence. There has been an enhancement in the intensity of the green emission centered at 547 nm, with increase in Ni concentration up to 0.5 at.% and a decrease in the intensity, observed for higher concentrations of Ni. However, the l(green)/I(blue) intensity ratio increases continuously with the increase in Ni concentration and also on prolonged UV irradiation of the samples. (C) 2010 Elsevier B.V. All rights reserved.