Aliphatic C-H bond functionalization associated with O-O bond activation on transition metal centers is the most attractive subject in the field of not only synthetic chemistry but also biochemistry. Reaction of hydroxo complexes of cobalt(II) and nickel(II), bearing hydrotris(3,5-diisopropylpyrazol-1-yl)borate, with ROOH (R = H, alkyl) results in oxygenation of the isopropyl substituents on the ligand.Mono- and dioxygenated Co(II) complexes 1 and 2 were obtained by treatment of the dinuclear Co(II) bis(μ-hydroxo) complex with a stoichiometric amount of H 2 O 2 and tBuOOH via dinuclear Co(II) μ-peroxo and mononuclear alkylperoxo intermediates, respectively. Fully oxygenated compound 3 was yielded by reaction of 2 with an excess amount of H 2 O 2 , and these observation suggested that repetitious oxygenation was proceeded via monomeric hydroperoxo intermediates.Reaction of the Ni(II) bis(μ-hydroxo) complex with H 2 O 2 also resulted in alkane functionalization, however it was different from that observed for the cobalt system. A ligand hydroxylated compound 4 was yielded by reaction of the hydroxo complex with a stoichiometric amount of H 2 O 2 . In contrast, treatment of the hydroxo complex with an excess amount of H 2 O 2 resulted in dehydrogenative oxygenation to give a μ-enolato complex 5.