In this work, Ni-P compounds were deposited on titanium hydride (TiH2) by the electroless plating method and the possible chemical reactions were studied in a broad temperature range of 100-1200 degrees C. The microstructure evolution and thermal decomposition mechanisms of Ni-P coated TiH2 were considered using characteristics of the coated powder samples treated at different temperatures. The characterization was carried out by X-ray diffraction analysis (XRD), energy dispersive spectroscopy (EDS) and field-emission scanning electron microscopy. It was shown that, up to 900 degrees C, no potential chemical reaction or deterioration of the Ni-P film occurs. However, the coating is partially swollen due to high back pressure of hydrogen gas behind the surface layer and some turgid islands are formed. At 1000 degrees C, the active mechanism of hydrogen release process begins to switch from internal diffusion to chemical reaction. At temperatures higher than 1000 degrees C, the coating becomes oxidized, some intermetallic or oxide compounds such as NiO, TiO2, NiTiHO0.95, TiNiH and Ti17P10 are formed and the hydrogenation state is reduced down to 1. Finally, it was found that in the temperature ranges of 100-900 degrees C, 900-1000 degrees C and 1000-1200 degrees C, the active mechanisms are internal diffusion, a combination of chemical reaction and internal diffusion, and chemical reaction, respectively. (C) 2016 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.