The Serra dos Reis A State Park is divided between the municipalities of Costa Marques (14.17%) and São Francisco do Guaporé (85.83%) in Rondônia.

[1] It adjoins the Serra dos Reis State Park along its southern boundary.

[2] The park is to the south of the BR-429 highway, east of the town of Costa Marques and north of the Guaporé River, which defines the border with Bolivia.

[2] The Serra dos Reis A State Park was created by decree 7.637 of 7 November 1996 with an area of about 2,243.85 hectares (5,544.7 acres) in the municipality of Costa Marques.

[5][3] The State Department of Environmental Development (SEDAM) was made responsible for administration.