In this study, bimetallic Ni/Fe nanoparticles were prepared and the ability of this material to degrade DDT in aqueous solution was investigated at room temperature. Besides comparing the degradation rates of DDT using monometallic zero-valent iron and bimetallic Ni/Fe, batch investigations with bimetallic Ni/Fe nanoparticles were conducted to explore the influence of pH value on the degradation rate of DDT in aqueous solution. Results indicate that weakly acidic (4 <= pH < 7) or alkaline reaction (7 < pH <= 10) conditions afford faster degradation rates, whereas higher or lower pH inhibits the DDT degradation. In addition, the DDT degradation exhibits an interesting pathway and mechanism at higher pH value (pH > 10) in reaction solution. In strong alkaline solution, the DDT degradation becomes slow but is not quenched. The electron transfer for DDT degradation is enhanced by creating numerous galvanic cells under the Ni catalysis, and promotes the dehydrochlorination reaction. The hydrodechlorination reaction in alkaline condition is also unbroken. This phenomenon is quite different from those reported in other studies previously. (C) 2008 Elsevier B.V. All rights reserved.