A LOCA in a fusion reactor involving an ingress of steam presents a safety concern due to hydrogen generated from steam reactions with plasma facing components. Hydrogen concentrations must be maintained below explosive levels. To support safety evaluations we have experimentally determined hydrogen generation rates when a tungsten alloy is exposed to steam from 400 degrees C to 1200 degrees C. We studied effects of steam pressure between 2.8 x 10(4) and 8.5 x 10(4) Pa, i.e., (0.28-0.84 atm) and gas velocity between 0.011 and 0.063 m/s. We present relationships for the reaction rates, oxidation phases, and mechanisms associated with the hydrogen generation. (C) 1998 Published by Elsevier Science B.V. All rights reserved.