This paper describes a novel heterogeneous catalytic oxidation process involving the use of hydrogen peroxide ( H2O2) with granular size iron oxide particles (FeOOH) in aqueous phase. The generation of hydroxyl radical (OH) in the process is demonstrated through the use of a probe chemical, n-chlorobutane (BuCl). Based on the experimental evidence, it is concluded that the OH, which is produced through the interaction of H2O2 with the surface sites, reacts with solutes adsorbed on the iron oxide surface, causing oxidation of the organic compounds. The generation rate of OH increases slightly with increasing pH in the range of 5-9. The oxidation rate of BuCl by OH is relatively insensitive to the pH and the level of bicarbonate ion in subject water due to low affinity of bicarbonate for the surface. Phosphate, on the other hand, inhibits the oxidation rate by preferential adsorption on the surface. This new process provides a viable alternative to the existing oxidation technologies, especially when water has high alkalinity and/or it is desired to oxidize target compounds that have high affinity for the surface selectively.