p-Benzoquinone reduction has been studied in aqueous solutions employing spectroelectrochemical techniques, and an intermediate species thus far believed to be unstable in aqueous media has been shown to be reasonably stable in unbuffered solutions. The detection of this intermediate species, which is produced as a one-electron transfer product, i.e. anion radical, suggests that the e(-)H(+)e(-)H(+) mechanism, in which e(-) and H+ represent electron transfer and protonation steps respectively, is a major reaction pathway during the electrochemical reduction of benzoquinone to the final product, hydroquinone, in unbuffered solutions. In buffered solutions, however, p-benzoquinone reduction is a two-electron process, as has been well known. A few anomalies discovered during the reduction of p-benzoquinone in aqueous media are discussed.