Fifteen rare earth-tetraphenylporphyrin(RE-TPP)complexes were directly prepared by mixing equalmolar concentrations of RE(ClO)and HTPP in acetone media.The electrochemical behaviors of these com-plexes and the influence of dissolved oxygen were investigated by voltammetry.Althrough there are some differ-ence between the behaviors of light and heavy rare earth-porphyrins,the central RE ions of the all fifteen com-plexes were reduced from tervalent to divalent state,meanwhile the dissovled oxygen was reduced as superoxideion O~-.which readily combined with the complex forming peroxide additive complex such as RE-TPP·O.