Fenton/Fenton-like reaction is often used as an efficient method to generate hydroxyl radicals (HO center dot) for bacteria inactivation in aqueous solution. However, inactivation efficiency of bacteria in aqueous solution using Fenton/ Fenton-like reactions needs to further improve as a result of transient generation of HO center dot. In this paper, we found that the formation of Tris-Co(II) complexes could decrease the redox potential of Co(III)/Co(II), facilitating the transformation of Tris-Co(III) complexes into Tris-Co(II) complexes. Therefore, HO' could be generated continuously in the presence of H2O2. Especially, Tris-Co(II) complexes are apt to combine with Escherichia Coli cells by electrostatic interactions, inducing a higher utilization ratio of the generated HO center dot. Therefore, the proposed Tris-Co(II) complex-H2O2 system could be employed as a high-efficiency sterilizing reagent for inactivation of E. Coli. This work provides a promising strategy for bacterial inactivation via an economic and eco-friendly manner.