Semiconducting nickel sulphide (NiS) thin films were deposited onto glass, fluorine doped tin oxide (FTO) coated glass and single crystal Si(1 1 1) wafer substrates using a new successive ionic layer adsorption and reaction (SILAR) method. The deposition conditions for obtaining good quality films such as concentration, pH and temperature of cationic and anionic precursor solutions, immersion and rinsing times and number of immersions were optimized. The XRD studies show that the crystallinity of Nis thin films depends on the nature of substrate. The optical band gap and activation energy were found to be 0.45 and 0.15 eV, respectively. Thermo-emf measurement revealed that the films are of p-type semiconductors.