Melstone is a town in far eastern Musselshell County, Montana, United States, along U.S. Route 12. The population was 136 at the 2000 census. The town was established in 1908 as a base for operating crews on the Chicago, Milwaukee, St. Paul and Pacific Railroad, then under construction in Montana. Although the railroad was abandoned in 1980, Melstone survives as a community center for farmers and ranchers in the lower Musselshell River valley.
Melstone is located at 46°35′57″N 107°52′11″W / 46.59917°N 107.86972°W / 46.59917; -107.86972 (46.599081, -107.869851).
According to the United States Census Bureau, the town has a total area of 0.7 square miles (1.8 km²), all of it land.