ZnS:Cu²⁺ nanocrystals were synthesized by co-precipitation method using zinc acetate dihydrate and sodium polyphosphate as precusors, copper(II) bromide as doping agent. The formation of ~ 2.2 nm sized nanocrystals was confirmed by X-ray diffraction studies.  Luminescent properties of the material was investigated by energy and time-resolved photoluminescence spectroscopy. Room-temperature photoluminescence spectra of ZnS:Cu²⁺ (0.8 mol%) nanoparticles under an excitation wavelength of 360 nm show two peaks at 440 nm and 570 nm. The 440 nm peak originates from the recombination of an electron from a shallow donor level at the Cu²⁺ impurity while the 570 nm peak is assigned to a transition between a deep donor level and the Cu²⁺ impurity. Time-resolved photoluminescence results indicate that these peaks show very short lifetimes: 7.8 ns for the 440 nm peak and 73.6 ns for the 570 nm peak.