CuS, In2S3, CuInS2 and CuGaS2 semiconductors have been synthesised in powder form by precipitation reaction using Na2S center dot 3H(2)O as a precipitating agent. Precipitated at about 313 K in aqueous medium, the powders of CuS crystallise in covellite (hexagonal) phase and those of In2S3, CuInS2 and CuGaS2 in tetragonal phase on heat treatment in argon atmosphere. The formation of CuS or In2S3 takes place due to the reaction between the metal and bisulphide ions in aqueous phase while that of CuInS2 or CuGaS2 involves solid state reaction between CuS and In2S3 or GaxSy during heat treatment and is accompanied with the evolution of SO2 gas. The powders are nearly monophasic, exhibit nanometric morphology and bear their respective stoichiometric compositions. The direct band gaps of CuS, In2S3, CuInS2 and CuGaS2 measure 2.06, 2.3,1.34 and 2.38 eV respectively. The method is simple and is extended to the synthesis of CuIn0.8Ga0.2S2 as well. (C) 2016 Elsevier Ltd. All rights reserved.