Irradiation of substituted 1,4-benzo- or 1,4-naphthoquinones in the presence of several aldehydes resulted in the formation of acylated hydroquinones in good yields. In the case of 5-acetyloxy naphthoquinone 8, both regioisomers were formed, but the 2,8-isomer was favored in all cases examined. Even acylated tetrahydroxy naphthalenes became available in good yields by this method.