In this article, the self-exchange electron transfer (ET) reaction NO2^-...NO2→NO2...NO2^- has been investigated by using the semiclassical model. The authors have focused on the influence of external electric field upon the diabatic potential energy surfaces and the temperature effect of the rate constant. It has been found that when the applied electric field reached a strength of 5.760× 10^9V.m^-^1, the energy barrier collapsed and therefore the ET reaction became a barrier-free one. It is interesting to note a new feature of the temperature effect on a nonadiabatic ET. Unlike those conclusions in simple collision theory and activated complex theory, there exists a maximum rate constant for a nonadiabatic ET as the value of temperature being 2Ec/R. Discussions have been made for this new feature.

Key words: ACTIVATION ENERGY, REACTION RATE CONSTANT, NITROUS ACID, FIELD EFFECT, TEMPERATURE EFFECT