Optimum conditions for pyrite removal from a high-sulfur coal by electrochemical reduction during flotation are determined by orthogonal experiments. The electrochemical reduction process of pure pyrite is examined with XRD, electrochemical and chemical analysis. The results show that the electrochemical reduction products of pyrite are FeS and S2-. During this process, the reactions at cathode are: FeS2 + 2e --> FeS + S2- and 2H(+) + 2e --> H-2. The corresponding electrode potentials and kinetic equation are determined. The conversion of hydrophobic pyrite to hydrophilic FeS and S2- by electrochemical reduction is beneficial to desulfurization from coal in floatation process. (C) 2004 Elsevier Ltd. All rights reserved.