Selective demethoxylation from aqueous guaiacol proceeded over Ru catalysts at relatively lower temperatures (≤433 K). Addition of MgO to the reaction media suppressed the unselective C–O dissociation. Cyclohexanol and methanol were obtained in high yield (>80%). A reaction route is proposed where partially hydrogenated guaiacol is decomposed into methanol and phenol, which is further hydrogenated to cyclohexanol.