Mathon (Romansh: Maton) is a former municipality in the Viamala Region in the Swiss canton of Graubünden. On 1 January 2021 the former municipalities of Casti-Wergenstein , Donat, Lohn and Mathon merged to form the new municipality of Muntogna da Schons .

Mathon is first mentioned about 840 as in Mentaune.

Mathon had an area, as of 2006, of 15.1 km2 (5.8 sq mi). Of this area, 66.3% is used for agricultural purposes, while 10% is forested. Of the rest of the land, 1.4% is settled (buildings or roads) and the remainder (22.3%) is non-productive (rivers, glaciers or mountains).