Massongex (French pronunciation: [masɔ̃ʒɛ]; Arpitan: Massongié) is a municipality in the district of Saint-Maurice, in the canton of Valais, Switzerland.

[3] Massongex has an area, as of 2009[update], of 6.6 square kilometers (2.5 sq mi).

[4] The municipality is located in the Saint-Maurice district, on the left side of the Rhone river.

The blazon of the municipal coat of arms is Gules, three Towers Argent masoned, windowed and doored Sable.

[8] Most of the population (as of 2000[update]) speaks French (1,218 or 92.3%) as their first language, German is the second most common (28 or 2.1%) and Italian is the third (24 or 1.8%).

[8] The historical population is given in the following chart:[3][12] The Tarnaiae, a Celtic and Gallo-Roman vicus is listed as a Swiss heritage site of national significance.

[15] In the 2007 Swiss Council of States election a total of 522 votes were cast, of which 30 or about 5.7% were invalid.

[8] There were 628 residents of the municipality who were employed in some capacity, of which females made up 39.2% of the workforce.

In the tertiary sector; 14 or 13.5% were in wholesale or retail sales or the repair of motor vehicles, 1 was in the movement and storage of goods, 10 or 9.6% were in a hotel or restaurant, 8 or 7.7% were in the information industry, 4 or 3.8% were the insurance or financial industry, 10 or 9.6% were in education and 36 or 34.6% were in health care.

[8] From the 2000 census[update], 1,010 or 76.6% were Roman Catholic, while 140 or 10.6% belonged to the Swiss Reformed Church.

The library has (as of 2008[update]) 4,340 books or other media, and loaned out 3,671 items in the same year.

It was open a total of 132 days with average of 6 hours per week during that year.