[en] Bone cancer is a malignant tumor that starts in the bone, where the cancer cells in the bone grow, compressing healthy bone tissue, causing extreme pain and can even be life threatening. To overcome the pain in the bones, a strong analgesic drug is needed, including morphine. ¹⁷⁷Lu EDTMP as a radiopharmaceutical for therapy can be used as an alternative for morfin to treat the pain caused by bone cancer, which has advantage as it can be administered to the patient only once in a few month just as other therapeutical radiopharmaceuticals. Currently, internal radiotherapy using radiopharmaceuticals of lutetium-177 ethylene diamine tetra methylene phosphonate (¹⁷⁷Lu EDTMP) is one of the best bone cancer treatments. In this study, labeling ¹⁷⁷Lu EDTMP was carried out by reacting EDTMP ligand with ¹⁷⁷Lu in the form of ¹⁷⁷LuCl₃ obtained from Lu₂O₃ irradiation in the GA Siwabesi multipurpose reactor and then the radionuclidic and radiochemical purity tests were carried out. Formulation solution of EDTMP was prepared in dry kit form using freeze drying method. This study was to optimize the incubation time and incubation temperature at the time of marking the EDTMP kit with ¹⁷⁷LuCl₃ and the effect of storage temperature for ¹⁷⁷LuEDTMP solution on stability, so that the optimum incubation time was 10 minutes at an incubation temperature of 25 °C which resulted in a radiochemical purity of 99.37 ± 0.5 %. The radiochemical stability test at storage temperature of 4 °C for 24 hours showed that this preparation was still stable with a radiochemical purity of 99.48 ± 0.31 %. (author)