[en] A new efficient approach for the preparation of ¹⁸⁸Re radiopharmaceuticals starting from [¹⁸⁸ReO₄]^-, produced at a carrier-free level through the ¹⁸⁸W/¹⁸⁸Re generator system, is described. The reaction procedure was based on the combined action of different reagents and has been applied in detail to the preparation of the therapeutic agent ¹⁸⁸Re(V)-DMSA (H₂DMSA [meso-2,3-dimercaptosuccinic acid]). The most efficient combination required the use of SnCl₂, oxalate ions, and γ-cyclodextrin. These were reacted with [¹⁸⁸ReO₄]^- and H₂DMSA to afford the final radiopharmaceutical in high radiochemical purity, at room temperature, and in weakly acidic solution. The role played by the various reagents in the reaction was investigated. It was found that SnCl₂ behaved as the actual reducing agent, whereas oxalate and γ-cyclodextrin greatly enhanced the ease of reduction of [¹⁸⁸ReO₄]^- through the action of two hypothetical mechanisms. In the first step of the reaction, oxalate ions gave rise to the formation of Re(VII) complexes with the concomitant expansion of the coordination sphere of the metal. This process strongly favored the electron transfer between Sn²⁺ and Re⁺⁷ centers, giving rise to intermediate reduced rhenium complexes. These species were further stabilized by the formation of transient host-guest aggregates with γ-cyclodextrin and finally converted into ¹⁸⁸Re(V)-DMSA through simple replacement of the coordinated ligands by H₂DMSA