Terbium-161 is a radioisotope characterized by β-emission, emission of Auger electrons, conversion electrons, and, to a lesser extent, gamma and X-rays. Tb-161 radioconjugate with the DOTA-PSMA-617 ligand (considered as a promising drug for radiotherapy of prostate cancer) was synthesized on the basis of components produced in Russian Federation. The physicochemical characteristics of 161Tb-DOTA-PSMA-617 were investigated. The ability of the radioconjugate to bind to cell membrane receptor was studied on cell line in vitro and in mice in vivo using a new CT26-PSMA cell model representing genetically modified mouse carcinoma cells expressing human PSMA. The pharmacokinetics and biodistribution of the radioconjugate were investigated. The radiopharmaceutical demonstrated highly specific accumulation in the tumor expressing human PSMA unlike in the control tumor. It was not significantly accumulated in the kidneys and other animals’ organs. The blood half-life time of the radiopharmaceutical was determined as 38.4 min. Thus, according to the main criteria, the synthesized radioconjugate 161Tb-DOTA-PSMA-617 is a promising radiopharmaceutical for the treatment of prostate cancer. © 2025 Elsevier B.V., All rights reserved.