The coating process of TiH2 particles with SiO2 layers, and the effect of the coating layer on gas release characteristic of TiH2 powders were studied experimentally. The pH value of reactive solution and gelation rate of silicic acid are important factors for controlling surface morphologies of coating layers. When pH value is about 4.0 and concentration of silicic acid is about 0.5 mol/L, respectively, the condensation rate of silicic acid is appropriate for the formation of a homogeneous and dense coating membrane. The results of gas release at 700 degreesC show that TiH2 particles coated with silicon dioxide layers can efficiently delay the starting time of gas release of TiH2 powders by 60-100s. (C) 2004 Elsevier Ltd. All rights reserved.