The effect of contact time on the removal of soluble organic matter by the intermittent contact oxidation process was studied. The process describes enhanced in-sewer purification through use of porous media with attached microorganisms which are exposed to sewage and sewer headspace-gas intermittently. Two lab-scale model channels, each installed with a plastic sponge sheet, were fed with a small volume of synthetic sewage for a short period. After feeding, the sponge sheet within each channel was exposed to headspace-gas for various durations ranging between 5–120 min. After exposure, tap water was introduced to wash away the remaining soluble organic matter. The oxygen consumption in the channel was monitored during and after sewage contact to evaluate the oxidation of the organic matter. Results showed that even with a short synthetic sewage contact time of 5–10 min, approximately 150 mgC L-sponge⁻¹ was removed per contact cycle. Soluble organic matter removal was positively influenced by non-flow condition extending up to 24 hrs. Microbial storage was suggested to play the key role in the removal of soluble organic matter. These findings support the effectiveness of the intermittent contact oxidation process for the removal of soluble organic pollutants when applied for in-sewer purification.