Adamantanes were successfully converted into the corresponding mono- and dihydroxy adamantanes with molecular oxygen in the presence of N-hydroxyphthalimide (NHPI) combined with cobalt salts under mild conditions. For example, exposure of adamantane under oxygen atmosphere in the presence of NHPI (10 mol%) and Co(acac)2 (0.5 mol%) in acetic acid at 75 °C for 6 h afforded adamantan-1-ol (43 %) and adamantane-1