The extraction of Co3+ from 0.1M aqueous acetate medium buffered to pH 5.3 by thenoyltrifluoroacetone (HTTA) in benzene and by 8-quinolinol (HQ) also in benzene at various temperatures has been studied. The species formed were Co(OH)2 (TTA)·(HTTA)2 and Co(Q3)·2HQ, respectively. 1,10-phenanthroline (Phen) as a base was also mixed with HTTA to form the species Co(OH)2(TTA)·(HTTA). Phen and Co(OH)2 (TTA)(HTTA)·2Phen. No synergism was observed upon the addition of Phen to HQ.