[en] Cocrystallization of Fmsup(2+) and Md⁺ with NaCl and KCl in aqueous-ethanol solutions in the presence of bivalent lanthanides is investigated. On the basis of thermodynamic study of the cocrystallization results it has been ascertained, that at the redox potential of Eusup(2+) mendelevium is reduced to oxidation state 1+ and it is cocrystallized with KCl and NaCl due to isomorphous cocrystallization. Fermium in the same medium is reduced by Smsup(2+) only to the oxidation state 2+ and forms anomalously mixed crystals (AMC) withKCl,at that, its cocrystallization coefficient increases linearly with Cl^- concentration increase inagreement with calculation. The dependences established show, that Md*H+ and Fmsup(2+) do not form stable chloride complexes and in this respect they are analogs of alkali and alkaline earth ions. The study of Md⁺ withSmF₂ and YbF₂ cocrystallization has shown, that in the systems AMC are formed in a similar way toAg⁺ cocrystallization with SrF₂