One of the methods of removing Fe(II) ions from drinking water is their oxidation and precipitation as ferric hydroxide Fe(OH)3. The catalytic effect of Fe(OH)3 flocs on the oxidation of Fe(II) has been investigated by several researchers [1, 2]. In this study, the catalytic effect of Fe(OH)3 slurries on the oxidation of Fe(II) was studied at three different pH values, 6.2, 6.5, and 6.7, with Fe(OH)3 concentrations ranging from 0 to 1000 mg/l using a batch reactor. The reaction rate constant (kcat) was found to increase linearly with increasing Fe(III) concentrations up to 500 - 600 mg/l decreasing again with higher concentrations. The model developed for the batch system was applied to a continuous system. The results showed that smaller reactors can be used due to the catalytic effect of Fe(OH)3 on Fe(II) oxidation.