Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Crystallization is an important industrial-scale process for the purification of enantiomers that depends on a phase diagram. In this work, the ternary phase diagram of R- and S-ketamine in ethanol was determined. The eutectic point indicated that crystallization of pure enantiomers from solutions containing more than 75% of the desired enantiomer is feasible. Solubility studies showed the feasibility of using temperature control to conduct the process. Batch crystallization of ketamine (S/R:80/20) solutions at 25 degrees C provided the isolation of S-ketamine (purity of 100%) with a yield from 65 to 70% and a productivity of 6.5 g/(1h).262427434Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)UnicampFundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)