Cauco is a former municipality in the district of Moesa in the Swiss canton of Graubünden. On 1 January 2015 the former municipalities of Arvigo, Braggio, Cauco and Selma merged to form the new municipality of Calanca.
The church at Cauco is first mentioned in 1497. The village was part of the Squadra di Calanca until 1851 when it became an independent municipality.
Before the merger, Cauco had a total area of 10.9 km2 (4.2 sq mi). Of this area, 8.8% is used for agricultural purposes, while 49.5% is forested. Of the rest of the land, 1.6% is settled (buildings or roads) and the remainder (40.1%) is non-productive (rivers, glaciers or mountains).
The former municipality is located in the Calanca sub-district of the Moesa district. It is located on the left bank of the Calancasca river at an elevation of 1,132 meters (3,714 ft). It is on a scree slope from a prehistoric rock slide. It consists of the village of Cauco and the hamlets of Lasciallo, Masciadone and Bodio (GR).