Remediation of industrial wastewaters represents a stringent problem in modern society, which requires particular understanding and ad hoc solutions. In this work, we performed extensive experimental study of chemical Fenton oxidation in order to understand the optimal operative conditions to be applied in real industrial wastewaters treatment. We analyzed the effectiveness of chemical oxygen demand (COD) removal from different wastewaters within a wide range of initial COD content. We observed a maximum COD % removal of about 80%, assessing the efficiency of the process. In order to understand the role of different reagents in the final yield, we performed a factorial experimental approach on the Fenton's reagents (H2O2 and Fe2+) and analyzed the results developing an analytical second-order model. The model depends on three variables, namely: the initial [CODi] of the sample, the [CODi]/[H2O2] ratio and [H2O2]/[Fe2+] ratio. We obtained an accurate description of the COD % removal in different initial conditions, with a R-2 = 0.85. In particular, we observed that optimal quantities of Fenton's reagents are a function of the initial COD of the treated wastes. (C) 2010 Elsevier B.V. All rights reserved.