According to the present invention, two hydroxyl groups can be introduced into the 1-position and the 4-position of the benzene ring of an aromatic compound highly efficiently and highly selectively by a one step process to give the corresponding aromatic hydroxide.The present invention provides a production method of an aromatic hydroxide represented by the formula (2) ##STR00001## wherein R.sup.1, R.sup.2, R.sup.3, and, R.sup.4 are each independently a hydrogen atom or an alkyl group having a carbon atom number of 1-20, and R.sup.1, R.sup.2 and/or R.sup.3 and R.sup.4 are optionally bonded to each other to form a ring, which comprises irradiating light to a photoelectrode comprised of metal oxide while applying a given potential in the presence of an aromatic compound represented by the formula (1) ##STR00002## wherein R.sup.1, R.sup.2, R.sup.3, and R.sup.4 are as defined above.