Simultaneous degradation of 4-chlorophenol (4CP) and Ethylenediaminetetraacetic acid (EDTA) was investigated in a heterogeneous Ultrasound/Fenton like system. In this system, zero valent iron (ZVI) was adopted and H2O2 was self-produced through oxygen activation catalyzed by iron/EDTA ligand reactions. It was found that pseudo first-order degradation kinetic was well applied for both 4CP and EDTA. The role of reaction components was discussed respectively and the effects of initial operating parameters on the degradation rate of 4CP and EDTA were investigated. The results showed that the competitive degradation relationship between 4CP and EDTA is weak. ZVI and EDTA are the essential components and they have important effect on the degradation of both compounds. Ultrasound (US) presented synergistic improvement on the degradation rate through overcome kinetic barrier of O-O band by ultrasonic cavitation effect. A non-radical degradation pathway seems credible and ferryl-EDTA complex ([Fe-IV O]EDTA) instead of OH is identified as the principal oxidant. (C) 2009 Elsevier B.V. All rights reserved,