The Bureau of Mines conducted solvent extraction batch tests to evaluate the usefulness of neodecanoic acid (nda) for extracting co3+ from ammoniacal leach liquors high in ammonium sulfate. This work is an outgrowth of previous Bureau research in which technology was devised for the recovery of cobalt, nickel, and byproduct copper from domestic laterites. The previously devised technology uses an oxidative ammoniacal sulfate leach to treat the laterite, and nickel and copper are then recovered from the leach solution by solvent extraction and electrowinning. This report deals with the subsequent solvent extraction of cobalt from the nickel-copper raffinate solution. The results showed that about 70 pct of the contained co3+ can be extracted batchwise at ph 8 using nda (a 10- carbon-chain highly branched carboxylic acid). However, nda had a solubility of approximately 0.6 to 0.8 G/l in aqueous raffinate following extraction, and this high solubility makes it impractical for use with alkaline solutions that are low in cobalt. In addition, the extracted cobalt species (predominantly cobaltic hexammine), is not amenable to the electrolytic recovery of cobalt metal because of its extreme stability. This fundamental problem, common to all extractants of the cobaltic ammines, is discussed, and an alternative for recovering cobalt metal from loaded solvent by a hydrogen-reduction method is also discussed.