The heat flux method for stabilizing flat adiabatic flames and measuring adiabatic burning velocities is reviewed. The latest improvements of the burner construction and analysis of the measurements are presented and a reliable error estimate is deduced. A consistent and reliable set of burning velocities has been measured for a range of fuels: new results for the adiabatic burning velocities of mixtures of methane, ethane, propane, n-butane, and isobutane with air are presented, including error bars of 95% confidence intervals. The influence of variations of initial temperature on the burning velocity of mixtures of methane and air has also been studied. The results are compared with other measurements using the heat flux, counterflow, and combustion vessel methods. It seems that results for the burning velocity using different methods converge toward each other. For stoichiometric flames of methane and air this value seems to be close to 36 cm/s, while the differences between the results of different techniques do not vary by more than roughly I cm/s. (C) 2003 The Combustion Institute. Published by Elsevier Inc. All rights reserved.