Extraction of microamounts of europium and americium by a nitrobenzene 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 cations HL⁺, HL ₂ ³⁺, ML ₂ ³⁺ and ML ₃ ³⁺ (M³⁺ = Eu³⁺, Am ³⁺) are extracted into the organic phase. The values of extraction and stability constants of the species in nitrobenzene saturated with water have been determined. It has been found that the stability constants of the corresponding complexes EuL _n,org ³⁺ and AmL _n,org ³⁺, where n = 2, 3 and L is TEtDPA, in the mentioned medium are comparable.