[en] Among the radiopharmaceuticals used for neoplasia, we can find the dimercaptosuccinic acid (Dmsa) labelled with ^99m Tc and ^186/188 Re. Initially, the ^99m Tc-(III)-Dmsa was employed as a renal image agent. Nevertheless, when it is prepared into a basic solution, the ^99m Tc-(V)-Dmsa complex is produced in high yield being cumulated by cells with a great metabolic activity. This property makes it a useful radiopharmaceutical for the detection of medullary thyroid carcinoma (MTC), soft-tissue tumors and other head and neck tumors. On the other hand, the renewed interest in β - emitting radionuclides, suggests that the ¹⁸⁶ Re-(V)-Dmsa complex could be used as antineoplastic agent in therapy. However, the techniques reported for the preparation of these compounds lack of stability studies and they are still in process of investigation, compromising to continue on the development of the radiopharmaceuticals by introducing new possibilities for better products already known, obtaining in this way, the approximation to the ideal radiopharmaceutical. The objective of this work is to design a freeze dried kit formulation for the instant preparation of ^99m Tc-(V)-Dmsa and ¹⁸⁶ Re-(V)-Dmsa complexes useful in the diagnostic and therapy of soft-tissue tumors and other head and neck tumors. We obtained a freeze dried stable formulation for the preparation of ^99m Tc-(V)-Dmsa kit with a radiochemical purity higher than 90 %, which fulfills with the quality control of radiopharmaceuticals. Furthermore, we developed analytical techniques for the determination of the different chemical compounds into the lyophilized kit. On the other hand, we obtained the optimum conditions for preparation of ¹⁸⁶ Re-(V)-Dmsa complex in high radiochemical yields (>90%). (Author)