Middletown is a city in Des Moines County, Iowa, United States.

[3] In 1940, the Iowa Army Ammunition Plant was established just to the south of Middletown.

[4] According to the United States Census Bureau, the city has a total area of 0.61 square miles (1.58 km2), all land.

There were 153 housing units at an average density of 278.7 per square mile (107.6/km2).

At the 2010 census there were 318 people in 127 households, including 94 families, in the city.

There were 148 housing units at an average density of 242.6 per square mile (93.7/km2).

The racial makeup of the city was 95.3% White, 1.6% African American, 1.6% Asian, 0.9% Pacific Islander, and 0.6% from two or more races.

At the 2000 census there were 535 people in 191 households, including 141 families, in the city.

There were 223 housing units at an average density of 364.8 per square mile (140.9/km2).