The extraction of Eu(III) and Am(III) vas investigated from nitrate medium by mixtures of thenoyltrifluoroacetone (HTTA) vith the soft donor ligands trlphenylamine, (Ph N) trlphenylarsine, (Ph As) or trlphenylphosphlne, (Ph P). Enhancement of the extraction of both metal ions vas observed for HTTA mixed vith either Ph As or Ph P. For the tvo cations investigated, Ph P shoved a greater synergic effect than Ph As. It vas found that the chemical formula of the main extracted species Is H(OH) (TTA)4HTTA.L for extraction by HTTA mixed vith either llgand (L). No specific preference for the synergic extraction of Am(III) over Eu(III) vas observed. For the tvo systems investigated, the mixed formation constant, £, for Eu(III) vas found to be alvays higher than that for Am(III)