Numerical computations are made of axisymmetric laminar jet diffusion flames taking into account detailed chemical kinetics and multicomponent diffusion. Two types of flames are investigated. The one is a usual flame that is formed around a fuel jet surrounded by an air flow. The other is an inverse flame formed around an air jet surrounded by the fuel (H2/N 2) flow. The computations predict significantly lower temperature (1250 K) near the flame tip than the maximum adiabatic equilibrium temperature (1660 K) of the original fuel in the usual flame. In the inverse flame, on the contrary, extraordinarily high temperature (2400 K) is predicted near the flame tip for the same fuel. These temperature characteristics in the two flames are verified by the laser Rayleigh scattering detection. It is revealed that such significantly lower or higher temperature than the adiabatic equilibrium temperature of the original fuel results from the preferential diffusion of heat and species which induces significant amount of excess and deficit of enthalpy and increase and decrease of H2 mole fraction in the flame. The processes of accumulation or dilution of H 2 species and excess or deficit of enthalpy are analyzed. Effects of the flame curvature are also investigated.