The effects of stretch and preferential diffusion on premixed flame behavior are studied for inwardly/outwardly propagating spherical flames in hydrogen/air mixtures. A local adiabatic equilibrium temperature is proposed as a measure of energy gain/loss caused by preferential diffusion" and flame stretch, which can be calculated from local and temporal concentrations and temperature during flame propagation. Various effects, including flame stretch, preferential diffusion, and adiabatic compression, can be explained based on local equilibrium temperature profiles for both inwardly/outwardly propagating lean and rich H2/air flames. A dip/jump in local equilibrium temperature profiles is observed which indicate fast hydrogen diffusion. Relative changes in burnt temperature compared to unburned temperature explain the energy gain/loss from preferential diffusion and stretch.