is a coastal town and a municipality in Østfold county, Norway. The administrative centre of the municipality is the town of Moss. The city of Moss was established as a municipality on 1 January 1838 (see formannskapsdistrikt). The rural municipality of Jeløy was merged with the city on 1 July 1943.
Its administrative district covers areas east of the town, such as the island of Dillingøy in the lake Vansjø. Parts of the town are located on the peninsula of Jeløy. Moss city has 30,723 inhabitants (2012).