New methods of extraction of Cs-137 and Sr-85 into solvent mixture of dodecanenitrile with n-dodecane in the presence of various crown ethers and chlorinated dicarbollide are described. This is the first time when extraction with chlorinated dicarbollide anion was accomplished into a judiciously chosen nonpolar solvent. The theoretical reasoning leading to the choice of such nonpolar solvent is outlined. New crown ethers with laterally branched alkyl chain were synthesized and tested. These, when the same crown moiety is compared, are more effective for Sr2+ extraction than the commonly used DC18C6 (18C6 ring moiety), but less effective for Cs+ extraction compared with DB21C7 (21C7 moiety). The systems may be used both in analytical applications and, hopefully, after further development, as well in a nuclear reprocessing industry.