Preparation and characterization of several supported metalloporphyrins are known, and have been evaluated as electrocatalysts for redoxreactions [l-6]. The support used was either the electrode itself or a polymer coating modification of the electrode surface. Modified organic polymer surfaces have also been reported as supports for metalloporphyrins [7, 81. In our search for new supported catalysts for olefin oxidation reactions, we have employed halogenated poly(siloxane) surfaces [9a] Sil-(CH&X, as supports for the metalloporphyrin catalyst, [Mn”‘(TPyP)]. Quatemization reactions have been used to bind the [Mn’n(TPyP)] species to the surface [9b]. We now report our studies of the effect of support on the electronic absorption spectra of several supported metalloporphyrins [M(TPyP)].