| Thonne-la-Long | |
| Commune Status: | Commune |
| Image Coat Of Arms: | Blason ville fr Thonne-la-Long 55.svg |
| Arrondissement: | Verdun |
| Canton: | Montmédy |
| Insee: | 55508 |
| Postal Code: | 55600 |
| Mayor: | Fabienne Thiery[1] |
| Term: | 2021 - 2026 |
| Intercommunality: | CC du pays de Montmédy |
| Coordinates: | 49.5622°N 5.4264°W |
| Elevation M: | 211 |
| Elevation Min M: | 207 |
| Elevation Max M: | 349 |
| Area Km2: | 9.5 |
Thonne-la-Long (pronounced as /fr/) is a commune in the Meuse department in Grand Est in north-eastern France.