The voltammetric oxidation of five para-substituted acetophenone derivatives (containing nitro, chloro, bromo, methyl and hydroxyl groups as substituents) and that of benzophenone was studied on a platinum and glassy carbon electrode in acetonitrile media. Electrode passivation was observed in the case when all selected compounds are on a glassy carbon electrode; an oxidation peak appeared between 2.5 and 3 V. The voltammograms of 4′-hydroxyacetophenone showed an additional peak around 2 V, which may be associated with the oxidation of the phenol moiety. In the case of a platinum electrode, no relevant peaks appeared on the voltammograms, reflecting the absence of passivation. The use of a redox probe 1,4-dihydroxybenzene showed that the glassy carbon electrode, after cyclization in the solutions of the outlined compounds, has higher sensitivity towards the oxidation product (1,4-benzoquinone) of this compound.