The Brookhaven National Laboratory (BNL) High-Temperature Combustion Facility (HTCF) was used to perform hydrogen deflagration and detonation experiments at temperatures to 650K, Safety features that were designed to ensure safe and reliable operation of the experimental program are described. Deflagration and detonation experiments have been conducted using mixtures of hydrogen, air and steam. Detonation cell size measurements were made as a function of mixture composition and thermodynamic gas conditions. Deflagration-to-detonation transition experiments were also conducted. Results of the experimental program are presented, and implications with respect to hydrogen safety are discussed.