The mixed sulphate/chloride leach liquor of manganese nodules bearing 11.8 iron, 24.8 copper, 0.23 zinc, 3.8 cobalt, 35.2 nickel, 176.3 chloride and 48.9 sulphate in g/L was processed for separation of Fe. Cu and Zn and the leach liquor free from Fe, Cu and Zn was used for separation of cobalt and nickel with 75% saponified 0.09 M and 0.7 M PC-88A, respectively in which the effect of pH, extractant concentration and organic to aqueous phase ratio was studied. For extraction of a mole of cobalt and a mole of nickel separately, two moles of the extractants were used to release a mole of H+ ion into the aqueous phase in each case. The extraction of cobalt was carried out in 2 stages at a 1:1 phase ratio, and extraction of nickel was carried out in 2 stages at an organic to aqueous phase ratio of 4:5. The extracted species were COA(2).3HA and NiA(2).3HA. The stripping of cobalt loaded organic was carried out with 5 g/L H2SO4 in 2 stages at an organic to aqueous phase ratio of 2:1, and stripping of the nickel loaded organic was carried out with 144 g/L H2SO4 in 2 stages at an organic to aqueous phase ratio of 1:4. (c) 2010 Elsevier B.V. All rights reserved.