In the present work, the investigations were firstly focused on the effect of microwave on the species distribution of ferric hydrolysates. as well as the effect of hydrolysates speciation on the treatment efficiency of organic compounds in the process of coagulation. A ferron-complexation timed spectrophotometric method was used to classify the Fe(III) speciation under different reaction conditions. Effects of microwave power, initial pH and reaction temperature on species distribution were intensively investigated. When microwave power and initial pH were 300W and 5, respectively, the amount of high polymeric ferric species, so-called Fe(c), reached its maximum. The increment of reaction temperature resulted in an increasing formation of Fe(c), and microwave was able to generate more Fe(c) than that of thermostatic method at the same temperature. Comparing with the treatment of pharmaceutical wastewater, the results indicated that Fe(c) facilitated the net rolling-sweep action for organic molecules in coagulation process, which enhanced the removal efficiency of entire reaction system. (C) 2010 Elsevier B.V. All rights reserved.