Abstract: The electronic structures of electrochemical reduction reaction in different steps for FeTPP and CoTPP have been studied by restricted CNDO/2 method. The results show that in the electrochemical reduction reaction of FeTPP the first electron interacts with d orbitals of the central Fe atom, whereas the second electron interacts with p orbitals of four nitrogen atoms, and eight carbon atoms connected with the four nitrogen atoms respectively. However, all the two electrons of CoTPPinteract with d orbitals of the central Co atom separately. This is in good agreement with the results obtained in an in-situ UVspectroscopic experiment.

Key words: FeTPP,CoTPP,CNDO/2 method, Electrochemical oxidation-reduction