For solvent extraction of Chromium (III) to be possible it is necessary that it react with an extractant thus forming a neutral complex with affinity for the organic phase. The objective of this work was to design and simulate a solvent extraction system of chromium (III) from an aqueous effluent using kinetic data from the literature. HDEHP (di (2-ethylhexyl) phosphoric acid) was used as the extractant. This work can be divided into three stages: in the first, a model of the kinetics of extraction as a function of time was develop from known kinetic data for an organic diluent, benzene. In the second step the developed model was used to predict the kinetics of four other diluents, n-hexane, kerosene, cyclohexane and carbon tetrachloride. For the choice of the organic diluent the behavior of the distribution ratio of chromium (III) in these diluents was evaluated over time. Safety and economic criteria were also evaluated. Finally, from the mass and energy balance equations we designed a liquid-liquid extractor operating in two stages whose objective was to have the lowest cost and for this we found the optimum solvent flow rates in the extraction at each stage.