Sphere-like CuGaS2 nanoparticles were successfully synthesized by a simple biomolecule-assisted solvothermal route using a mixed solution compose of ethylenediamine and distilled water (1:1, v/v), in which L-cystine was used as the sulfide source and complexing molecule. Phase analysis was carried out by X-ray diffraction (XRD) and the results confirmed the as-prepared CuGaS2 as a single-phase tetragonal structure. Field-emission scanning electron microscope (FESEM) and transmission electron microscope (TEM) showed that the morphologies of CuGaS2 were sphere-like nanoparticles in shape, and the average diameters was about 600 nm. X-ray photoelectron spectrum (XPS) was used to analyze the composition of CuGaS2 and the ratio of Cu/Ga/S is 1:0.97:1.98. Raman spectrum of the obtained CuGaS2 exhibit a high-intensity peak of the A1 mode at 305 cm(-1). The influence of reaction temperature, time and solvent was initially investigated. The possible formation mechanism was also discussed. (C) 2011 Elsevier B.V. All rights reserved.