[en] Extractions of ¹³⁷Cs by the polyhedral complex H⁺[(π)-3-(1,2-B₉C₂H₁₁)₂Co^-], further referred to as dicarbolide-H⁺, in nitrobenzene from fresh and sour milk and milk with proteins precipitated by nitric acid were examined. The effect of the extractant concentration was assessed. The results showed that the extraction can be quantitative from any sort of milk at one order lower amount of isotopic carrier than the amount of the extractant. The retention of ¹³⁷Cs on protein precipitate in the course of multiple decantation was evaluated. The distribution ratios at various concentrations of nitric acid in milk were determined and the effect of dilution of milk before extraction was assessed. The results showed that the distribution ratios of ¹³⁷Cs from diluted milk are over 10³ and there are conditions under which the extraction is highly selective. A procedure for quantitative extraction of ¹³⁷Cs from milk was suggested. (author)