We discovered that chemically reduced graphene oxide, with an I D/I G >1.4 (defective to graphite) can effectively activate peroxymonosulfate (PMS) to produce active sulfate radicals. The produced sulfate radicals (SO 4 •̄) are powerful oxidizing species with a high oxidative potential (2.5-3.1 vs 2.7 V of hydroxyl radicals), and can effectively decompose various aqueous contaminants. Graphene demonstrated a higher activity than several carbon allotropes, such as activated carbon (AC), graphite powder (GP), graphene oxide (GO), and multiwall carbon nanotube (MWCNT). Kinetic study of graphene catalyzed activation of PMS was carried out. It was shown that graphene catalysis is superior to that on transition metal oxide (Co 3O 4) in degradation of phenol, 2,4-dichlorophenol (DCP) and a dye (methylene blue, MB) in water, therefore providing a novel strategy for environmental remediation.