Iron disulfide can be used as an alternative material in high technological systems, as an example, solar energy collectors and cathodic component in primary and secondary batteries. The present work studies the kinetics and thermodynamics of the iron disulfide synthesis in a fluidized bed reactor for temperatures varying from 400ºC to 500ºC, operating in the bubble fluidized bed regime. It was observed that the synthesis conversion is much dependent on control variables: inert gas flow, temperature, sulfur gas partial pressure, nature of raw materials and reaction time. In favorable experimental conditions, that is 60 minute time reaction and 500ºC temperature, it was achieved more than 95% iron oxide conversion in iron disulfide, generating particle aggregates with distribution size between 100Âum and 200Âum, uniform morphology with ellipsoidal appearance. Manual desagragation leads to small iron disulfide particles with 1,4 Âum average size, ideal for electrochemical use. The iron disulfide phase quantification was performanced by the Rietvelt method associated with Powder Difraction technique. The results showed that it is possible, within a pyrometallurgy route, to synthesize iron disulfide for electrochemical applications, from cheap and easy obtainable reagents such as iron oxide and elemental sulphur.