Relative to the catalyst-free reaction system, the concentration and total toxic equivalent values of 2,3,7,8-PCDFs decreased by 24.1-99.7% and 86-98.4%, respectively, in the NiFe 2 O 4 catalyst system, while initial increases by 744.5% and 426.3%, respectively, followed by reduction up to 81.6% and 90.7%, respectively, were observed in the Fe 2 O 3 catalyst system. Current findings indicate that NiFe 2 O 4 hindered PCDF formation, which was attributed to its chemical structural stability and high activity towards degradation of biphenyl-like constituents in PCBs.