The laminar burning velocity;(LBV) of a gaseous fuel/oxidant feed is a strong function of the feed mixture composition. In this paper, published LBV values are successfully correlated with the square root of the ratio of the thermal diffusivity of the fuel/oxidant feed mixture to the space time at extinction of a hypothetical perfectly stirred reactor (PSR) burning this feed. The PSR simulations use detailed reaction mechanisms. A wide range of hydrocarbon and inorganic fuels and oxidants are considered.