Intermediate products such as MHP (Mixed Hydroxide Precipitate) are processed by solvent extraction which is a continuous process in industry for obtaining final product such as nickel metal or nickel sulphate. Nickel is used essentially in stainless steel industry and cobalt is used in super alloys. Both metals are used in lithium-ion battery technologies especially electrical vehicles. A preliminary stage of solvent extraction process is called as pre-neutralisation and it is based on partial neutralisation of the acidic organic reactant to prevent pH fluctuations in extraction due to the H+ ions release aqueous phase, and it provides an exchange mechanism to enable loading of the metals to the organic phase. In this thesis study, it is aimed to optimise the organic phase pre-neutralisation percent in further purification treatment of MHP leach solution (PLS-Pregnant Leach Solution) from Gordes nickel laterites and investigate its effect on extraction by D2EHPA and Cyanex 272 organic reactants. NaOH and Na2CO3 solutions were used in pre-neutralisation with 35%, 40% and 45% in D2EHPA and 30%, 35% and 40% in Cyanex 272. The optimum pre-neutralisation results were found as 35% for D2EHPA and 30% for Cyanex 272.