We report on the fabrication and characterization of high-temperature Pt-TSVs. A LPCVD silicon nitride passivation layer was implemented to protect the TSVs from oxidation during high-temperature treatments and wet HF-based post-processing steps, the later being widely used for the release of MEMS mechanical structures. An ohmic contact between the TSV metallization and a silicon device layer was created and maintained, during and after high-temperature treatments. These “via first” TSVs were able to withstand post-processing temperatures up to 850 °C; the specific contact resistance was investigated. Moreover, they are of interest for high temp- perature applications; they operated stably for at least 24 h at up to 450°C.