In the present work, conditions were set for a study of the effect of field geometrical structure, by its transition from uniform to non-uniform field by varying the ratio of anode and cathode active areas on the effective oxidation level, assumed to be a measure for non-conformity with Faraday law by the anodic dissolution of aluminum in solutions of sodium chloride. Nonconformity with Faraday law was observed as in the range of low current densities (lower than 80-150 Am-2) the effective oxidation level changes in a wide interval depending on the factors studied and electric field geometry; in the range of high current densities (higher than 80-150 Am-2) the effective oxidation level. is slightly affected by the electric field geometry and conditions used.