A process for the separation of nickel, cobalt or both from impurity elements selected from one or more of calcium, magnesium, manganese and chloride contained in a leach solution, the process comprising the step of subjecting the leach solution to solvent extraction using a carboxylic acid (such as Versatic 10), a hydroxyoxime such as LIX 63, a kinetic accelerator such as TBP, and optionally a stabilizer.