The ability of inorganic hydroxide sorbents Termoxid-5 (T-5) and Termoxid-39 (T-39) heat-treated at temperatures from 100 to 950°C to take up radionuclides of the ²²⁵ Ac subfamily was examined in a wide range of solution acidities and salt compositions. T-5 and T-39 are principally suitable for the development of both direct and inverse ²²⁵ Ac/ ²¹³ Bi generators with the activity of hundreds of millicuries of ²²⁵ Ac.