A new correlation describing the laminar burning velocity of hydrogen/air mixtures as a function of temperature, pressure, and mixture composition is proposed. The correlation is developed for reactive hydrogen/air mixtures diluted with steam for wide temperature, pressure, and composition ranges. The study includes the following stages: first, the laminar burning velocity was calculated with the detailed reaction mechanism of Maas and Warnatz (1988) implemented in the code INSFLA; second, the results obtained were validated against experimental data and a new heuristic approximation based on them was created. The correlation found consists of simple mathematical expressions and provides a good approximation of the laminar burning velocity in the range between 200 K and 600 K for temperature, between 0.1 bar and 10 bar for pressure, and up to 20 mol% steam dilution.