| Masio | |
| Official Name: | Comune di Masio |
| Coordinates: | 44.8667°N 32°W |
| Region: | Piedmont |
| Province: | Alessandria (AL) |
| Frazioni: | Abazia |
| Mayor: | Pio Giuseppe Perfumo |
| Area Total Km2: | 22.3 |
| Population Total: | 1481 |
| Population As Of: | 2005[1] |
| Population Demonym: | Masiesi |
| Elevation M: | 142 |
| Postal Code: | 15024 |
| Area Code: | 0131 |
Masio (Mas in Piedmontese) is a comune (municipality) in the Province of Alessandria in the Italian region Piedmont, located about 60km (40miles) southeast of Turin and about 20km (10miles) southwest of Alessandria.
Masio borders the following municipalities: Cerro Tanaro, Cortiglione, Felizzano, Incisa Scapaccino, Oviglio, Quattordio, and Rocchetta Tanaro.