In a process for producing phenol or a substituted phenol, an alkylaromatic hydroperoxide having a general formula (I): in which R1 and R2 each independently represents an alkyl group having from 1 to 4 carbon atoms, provided that R1 and R2 may be joined to form a cyclic group having from 4 to 10 carbon atoms, said cyclic group being optionally substituted, and R3 represents hydrogen, one or more alkyl groups having from 1 to 4 carbon atoms or a cyclohexyl group, is contacted with a catalyst comprising an oxide of at least one metal from Groups 3 to 5 and Groups 7 to 14 of the Periodic Table of the Elements and an oxide of at least one metal from Group 6 of the Periodic Table of the Elements.