A novel reductant, amorphous FeS2 (FeS2(am)) was synthesized to remove hexavalent chromium (Cr(VI)). The stoichiometry, kinetics and mechanisms of FeS2(am) induced Cr(VI) reduction were studied under anaerobic conditions with a pH range of 5.0-13.0. Results showed that FeS2(am) was efficient in removing aqueous Cr(VI) with a stoichiometry of Cr(VI): FeS2(am) similar to 1: 0.9. Moreover, the reduction kinetics decreased with the growth of pH within the pH range from 5.0 to 10.0, but increased within pH 10.0-13.0. The dissolution kinetics of FeS2(am) was found to be mainly responsible for the varied Cr(VI) reduction kinetics, and the mechanisms involved in the reduction process were further confirmed by X-ray photoelectron spectroscopy analysis. In addition, O-2 was found to compete with Cr(VI) in the reduction process and subsequently impede the Cr(VI) reduction rate. (C) 2016 Elsevier B.V. All rights reserved.