Extraction of strontium by the nitrobenzene solution of bis-1,2-dicarbollylcobaltate in the presence of dibenzo-18-crown-6 (DB18C6, L) has been investigated. the equilibrium data and the typical maxima concerning the dependencies of the Sr distribution ratios on the total analytical concentration of DB18C6 in the system under study can be explained assuming that the particles Sr2+, SrL2+, SrL22+, SrHL3+ and SrHL23+ are extracted into the nitrobenzene phase. The values of the corresponding extraction and stability constants of the extracted species in nitrobenzene saturated with water have been determined.