A novel [FeFe]-hydrogenase biomimetic catalyst [(mu-dmedt)Fe-2(CO)(5)] (mu-DPPF-O) (1) was prepared by CO-substitution in the (mu-dmedt)[Fe-2(CO)(6)] complex with DPPF in THF. Confirmation of the catalyst structure was determined by FTIR, H-1 NMR, C-13 NMR, P-31 NMR and single crystal X-ray diffraction. Complex 1 exhibited better catalytic reactivity for phenol hydroxylation than the all-carbonyl complex (mu-dmedt)[Fe-2(CO)(6)]. The dihydroxybenzene selectivity of 94.0% and phenol conversion of 42.9% were obtained under the optimal reaction conditions. The relationships between electron density of the Fe-Fe bond and the catalytic activity of these complexes were revealed, which showed that the more electron rich the Fe-Fe bond is, the better catalytic hydroxylation activity was achieved.