A high-throughput smartphone-based colorimetric reader (HSCR) was developed to quantitatively detect hypochlorite in aqueous solution and determine hypochlorite scavenging capacity in high-throughput format by a blue probe DMMA-IR780, which changes from deep blue to pink upon epoxidation by hypochlorite on one of the double bonds. The reaction mechanism between probe and hypochlorite was study by mass spectrum and attribute to the formation and degradation of chlorohydrins. The color change was recorded by a smartphone-based colorimetric reader to apply into an android-based application for on-site determination and analysis. This portable system could quantify hypochlorite with linearity range of 0.43 to 875 mu M and limit of detection at 0.08 mu M. Taking advantages of smartphone and probe DMMA-IR780, the assay provides a cost-effective and hand-held platform for on-site HOCl determination and quantification of hypochlorite scavenging capacity of dietary antioxidants.