Measurements of laminar adiabatic burning velocities of flames propagating in hydrogen-oxygen-nitrogen mixtures at atmospheric pressure are presented and analyzed in this study. The oxygen content in the oxidizer (nitrogen-oxygen mixture) was varied between 0.07 and 0.1 (7-10 volume percent) at an equivalence ratio of 1.058. Besides the variation in oxygen content a variation in equivalence ratio from 0.7 to 3.1 and from 0.7 to 0.95 is presented at oxygen contents of 0.077 and 0.1077, respectively. The heat flux method was used to determine burning velocities under conditions where the net heat loss of the flat stretchless flame to the burner is zero. The resulting adiabatic burning velocities are presented with error margins using a 95% confidence interval. A significant difference was found when comparing the present results with experimental data from the literature.