The characteristic rich shifting of the maximum adiabatic flame temperature from the stoichiometric value for mixtures of hydrocarbon and air is demonstrated to be caused by product dissociation and hence reduced amount of heat release. Since the extent of dissociation is greater on the lean side as a result of the stoichiometry of dissociated products, the peaking occurs on the rich side. The specific heat per unit mass of the mixture is shown to increase monotonically with increasing fuel concentration, and as such tends to shift the peak toward the lean side. It is further shown that this is the cause for the lean shifting of the adiabatic flame temperature of oxidizer-enriched mixtures of NmHn and F-2 and of NH3 and O-2, with various amounts of inert dilution, even though their maximum heat release still peaks on the rich side. (c) 2006 The Combustion Institute. Published by Elsevier Inc. All rights reserved.