NiO thin films were synthesised on glass substrates at room temperature using the Successive Ionic Layer Adsorption and Reaction (SILAR) method. The effect of film thickness on the structural, morphological, optical and electrical properties of NiO thin films was investigated. The X-ray diffraction (XRD) and scanning electron microscopy (SEM) studies showed that all the films exhibit polycrystalline structure are covered well with glass substrates. The crystalline and surface properties of the films improved with increasing film thickness. The energy band gap values were decreased from 3.71 to 3.67 eV depending on the film thickness. The refractive index (n), optical static (epsilon(o)) and high frequency dielectric constant (epsilon(infinity)) values were calculated by using the energy band gap values as a function of the film thickness. The resistivity of the films varied between 4.1 and 802.1 Omega cm with increasing film thickness at room temperature. (C) 2014 Elsevier B.V. All rights reserved.