This paper reports the synthesis of magnetic CoFe2O4-reduced graphene oxide (rGO) hybrids and the catalytic performance in heterogeneous activation of peroxymonosulfate (PMS) for decomposition of phenol. The surface morphologies and structures of the CoFe2O4-rGO hybrids were investigated by field emission scanning electron microscopy (SEM), energy-dispersive X-ray spectrometer (EDS), transmission electron microscopies(TEM), powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), nitrogen adsorption-desorption isotherm, and thermogravirnetric analysis (TGA). Through an in situ chemical deposition and reduction, CoFe2O4-rGO hybrids with CoFe2O4 nanopartides of 23.8 nm were produced. Catalytic testing showed CoFe2O4-rGO hybrids exhibited much better catalytic activity than CoFe2O4, which suggests rGO plays an important role in CoFe2O4-rGO hybrids for the decomposition of phenol. Moreover, the hybrid catalyst presents good magnetism and could be separated from solution by a magnet.