Extraction of microamounts of europium and americium by a phenyltrifluoromethyl sulfone (FS 13) solution of hydrogen dicarbollylcobaltate (H⁺B^-) in the presence of N,N,N′,N′- tetraethyl-2,6-dipicolinamide (TEtDPA, L) has been investigated. The equilibrium data have been explained assuming that the species HL⁺, HL ₂⁺, ML₂^{3 +} and ML₃ ³⁺ (M³⁺ = Eu³⁺, Am³⁺) are extracted into the organic phase. The values of extraction and stability constants of the cationic complex species in FS 13 saturated with water have been determined. It was found that the stability constants of the corresponding complexes EuL _n³⁺ and AmL_n³⁺, where n = 2, 3 and L is TEtDPA, in the mentioned FS 13 medium are comparable.