Abstract: A Prussian blue derived C-Co catalyst was synthesized and used to activate peroxymonosulfate (PMS) for the degradation of methylene blue. The C-Co catalyst exhibited higher catalytic performance than that of Co₃O₄, reaching degradation rate of 90.0% for 30 mg·L^-1 methylene blue in 40 minutes. The reaction process was fitted by the pseudo-second order kinetic model, and the reaction rate constant was 1.57×10³ L·mol^-1·min^-1. The effect of temperature, pH, PMS concentration and coexisting ions on methylene blue degradation rates were also investigated during the activation of PMS by C-Co. The reactive radicals in the reaction were further explored by free radical trapping experiments. The results demonstrate that the singlet oxygen produced by PMS activation played an important role in methylene blue degradation. Moreover, C-Co had a good reusability, keeping a high degradation rate after having been reused for three times.