We have studied the electrochemical behavior of natural pyrite (FeS1.9, n-type semiconductor) treated nonaqueously with dimethylsulfoxide (DMSO) solvent and also with a gelatin/DMSO solution. Composite electrodes (comprised of pyrite, polyvinilidene fluoride, polyethylene oxide and carbon) were characterized in a lithium cell at room temperature by cyclic voltammetry and galvanostatic measurements; the electrolyte used was LiPF6 in a solution of ethylene carbonate and dimethyl carbonate (1 mol 1(-1)). The gelatin/DMSO treatment greatly improved the reversible specific capacity of a pyrite electrode. For galvanostatic discharge/charge at a current density of 0.4 mA cm(-2) and between voltage limits of 3.2 and 1.1 V, its reversible specific capacity at the 15th cycle equaled 275 mA h g(-1), an impressive value compared to less than 25 mA h g(-1) for a pristine pyrite electrode.