Sorption of stable and radioactive strontium ions onto mesoporous manganese oxide of OMS-2 type, prepared by the sol–gel method via reduction of potassium permanganate with polyvinyl alcohol in aqueous medium, was studied. The influence exerted by the pore structure parameters and by the phase and chemical composition of manganese oxide on its sorption properties and selectivity to Sr ions was examined. Manganese oxide samples prepared using a 0.1 wt % KMnO4 solution exhibit the highest values of the sorption capacity for Sr, about 100–150 mg g–1, and of the Sr distribution coefficient, Kd = (11.5–19.5) × 103 cm3 g–1. Introduction of 0.1 M NaCl into this solution considerably decreases the sorption of stable Sr ions, and for all the samples the sorption capacity is 25–35 mg g–1. On the other hand, for the most active sorbents the distribution coefficient in the presence of 0.1 M NaCl increases by a factor of approximately 8–10 relative to distilled water and reaches (91–208) × 103 cm3 g–1. Introduction of 0.05 M CaCl2 also decreases the Sr uptake, and the sorption capacity of the most active sorbents for stable Sr ions is 25–35 mg g–1 at Kd(85Sr) equal to (0.14–0.35) × 103 cm3 g–1.