The kinetics and mechanism of a simple system, Co2+-HCO3--H2O2 for degrading highly stable organic pollutants have been reported. Fast and versatile decolorization of organic dyes was observed in an aqueous solution containing 10 mM NaHCO3, 10 mu M Co2+ ions and 10 mM H2O2, while the degradation rate of p-nitrophenol and 2,4-dinitrophenol was very slow. From cyclic voltammetry and UV-vis spectra, it was found that different complexes between Co2+ ions and methylene blue (MB) were formed in HCO3- solution, and being confirmed by photoluminescence probing and electron spin resonance spin-trapping technologies, the 1:1 complex [Co-II(HCO3-)(MB)](+) was more efficient in catalyzing decomposition of H2O2 into (OH)-O-center dot radicals. The other tested pollutants also played an important role in the rate of (OH)-O-center dot radicals production in the system. Based on the kinetic observations of MB decolorization, a possible mechanism was proposed. (C) 2011 Elsevier B.V. All rights reserved.