Five isomorphous 3D complexes of formates, namely, {Cu(HCOO)·4HO} ( 1), {Co(HCOO)·2HO} ( 2), {Mn(HCOO)·2HO} ( 3), {Co(HCOO)·DMF·HO} ( 4), and {Mn(HCOO)·0.5[HN(CH)]} ( 5), were synthesized and characterized by microanalysis. The catalytic activities of these complexes for the oxidation of phenol by HO to catechol (CAT) and hydroquinone (HQ) were investigated. Complex 1 showed the best performance by exhibiting a high conversion rate of 68.02% and a high selectivity for CAT with a maximum CAT/HQ ratio of 2.74. [ABSTRACT FROM AUTHOR]