Ammonia has become an important source for hydrogen especially for fuel cell applications that require COx free hydrogen. In this study, high surface area Pt incorporated mesoporous siliceous materials were prepared for ammonia decomposition reaction to produce clean hydrogen. The results of a fixed bed flow reactor tests, conducted using pure ammonia showed that Pt-SiO2 type catalysts which were prepared by a one-pot hydrothermal synthesis procedure were very active in ammonia decomposition, such as 72% conversion was reached at 500 degrees C at a gas hourly space velocity of 5,100 ml/h.g(cat) over the catalyst prepared at Pt/Si mol ratio of 0.03. Activity of the synthesized catalysts increased with an increase in Pt loading. Platinum incorporated siliceous materials prepared by impregnation procedures were also tested in ammonia decomposition and highly promising results were obtained.