The photocatalytic degradation of three hydroxylated bicyclic aromatic compounds (2,2’-dihydroxybiphenyl, 4,4’-dihydroxybiphenyl and 4-hydroxybiphenyl) in contact with TiO2, in aqueous unbuffered solution was achieved. The main intermediate, in all cases, was 1,2,4-trihydroxybenzene. The photoxidation of this intermediate led to identified compounds : maleic acid, muconic acid and butadiene, resulting from the aromatic ring opening. A complete mineralization scheme for hydroxylated bicyclic aromatic compounds can be proposed.