This paper addresses the structural characteristics and phase transformation behaviour of plain electroless Ni-P coating and electroless Ni-P-Si3N4, Ni-P-CeO2 and Ni-P-TiO2 composite coatings. The X-ray diffraction patterns of electroless Ni-P-Si 3N4, Ni-P-CeO2 and Ni-P-TiO2 composite coatings are very similar to that of plain electroless Ni-P coating, both in as plated and heat-treated conditions. Selected area electron diffraction (SAED) patterns obtained on the Ni-P matrix of Ni-P-Si 3N4, Ni-P-CeO2 and Ni-P-TiO2 composite coatings exhibit diffuse ring patterns resembling the one obtained for plain electroless Ni-P coating. Phase transformation behaviour studied by differential scanning calorimetry (DSC) indicates that the variation in crystallization temperature and the energy evolved during crystallization of plain electroless Ni-P coating and electroless Ni-P-Si3N 4, Ni-P-CeO2 and Ni-P-TiO2 composite coatings is not significant. The study concludes that incorporation of Si 3N4, CeO2 and TiO2 particles in the Ni-P matrix does not have any influence on the structure and phase transformation behaviour of electroless Ni-P coatings. © 2005 Elsevier Ltd. All rights reserved.