The aim of the present work is to investigate the interaction between a water spray and a laminarhydrogen-air flame in the case of steam inerted mixture. A first work is devoted to study thethermodynamics involved in the phenomena via a lumped parameter code. The flow is two-phase andreactive, the gas is multi-component, the water spray is polydisperse and the droplet size has certainlyan influence on the flame propagation. The energy released by the reaction between hydrogen andoxygen vaporizes suspended droplets. The next step of this study will be to consider a drift-flux modelfor the droplets and air under hypotheses that the velocity and thermal disequilibria are weak. Themulti-component feature of the gas will be further taken into account by studying a gas mixturecontaining hydrogen, air and water vapor. A second study concerns an experimental investigation ofthe effect of droplets on the flame propagation using a spherical vessel. A Schlieren system is coupledto the spherical vessel in order to record the flame propagation on a digital high speed camera. Bothstudies will help improve our knowledge of safety relevant phenomena.