The effect of temperature on the adiabatic laminar burning velocities of CH4 + air and H-2 + air flames was analyzed. Available measurements were interpreted using correlation S-L = S-LO (T/T-o)(alpha). Particular attention was paid to the variation of the power exponent a with equivalence ratio at fixed ( atmospheric) pressure. Experimental data and proposed empirical expressions for a as a function of equivalence ratio were summarized. They were compared with predictions of detailed kinetic models in methane + air and hydrogen + air flames. Unexpected non-monotonic behavior of alpha was found in rich methane + air flames. Modeling results are further examined using sensitivity analysis to elucidate the reason of particular dependences of the power exponent alpha on equivalence ratio. (C) 2009 Elsevier Ltd. All rights reserved.