The redox behaviour of compounds in sesame oil was investigated directly by cyclic voltammetry (CV) in 1 M sulfuric acid. The oil was used as a pasting material for a carbon paste electrode (CPE). CV curves measured on the CPE showed the redox behaviour of redox active compounds to be more concentrated than ca. 0.01%. The characteristic CV curve of sesame oil has been attributed to the reactions of sesaminol and sesamol. Electrochemical oxidation of sesaminol and sesamol in 1 M sulfuric acid took place at the methylenedioxy and para-hydroxy groups, affording substituted and unsubstituted hydroxybenzoquinones. Mechanisms for the electrochemical reactions are proposed on the basis of the behaviour of model compounds.