We investigated the oxidation of 2,4-dinitrotoluene (DNT) by persulfate ($S_2O_8^{2-}$) activated with steel waste powder via a series of batch experiments. We hypothesized that the addition of steel waste powder into a persulfate-water system would enhance the oxidation of DNT with activated persulfate. Compared to reductive transformations of DNT by steel waste powder, DNT was rapidly removed via oxidation by steel waste powder-activated persulfate and through reduction by steel waste powder in a steel waste powder-persulfate system. As the amount of steel waste powder increased, removal of DNT increased until there was complete removal in the presence of 10 g of steel waste powder and 250 mg/L of persulfate under the given conditions. In contrast, additions of $Fe^{2+}$ resulted in only 20% removal by $Fe^{2+}$ -activated persulfate under identical conditions. Oxidation of reductive products of DNT (2-amino-4-nitrotoluene, 2-nitro-4-aminotoluene, and 2,4-aminotoluene) by steel waste powder-activated persulfate was significantly enhanced as reduction proceeded. Our results suggest that DNT may be effectively removed by steel waste powder and/or steel waste powder-activated persulfate in soils and aquifers.