The voltammetric behaviour in alkaline solution of a nickel-based chemically modified electrode (poly-NiTMHPP) prepared by oxidative electropolymerization of a nickel tetrakis(3-methoxy-4-hydroxyphenyl)porphyrin for electro-oxidation of methanol was investigated by cyclic voltammetry and the rotating disk technique. The oxidation of methanol occurs at 0.61 V vs. SCE, where oxidation is not observed at the bare electrode. The dependence of the oxidation current on the methanol concentration and on the number of redox centres Ni(II)/Ni(III) is discussed. From the fact that the oxidation current increases with increasing film thickness it is evident that the electrocatalytic reaction occurs inside the polymer film. The system examined is a typical example of a redox polymer with 3D properties. It is also concluded that the reaction mechanism of methanol electro-oxidation is of the so-called "R" case, according to the concept of Saveant and Andrieux, i.e, a cross-exchange reaction is the limiting step.