The Despreux River is a tributary of the Harricana River, flowing into the municipalities of Eeyou Istchee Baie-James (municipality), in Jamésie, in the administrative region from Nord-du-Québec, in Quebec, in Canada.

The surface of the river is usually frozen from early November to mid-May, however, safe ice movement is generally from mid-November to the end of April.

The main hydrographic slopes near the Despreux River are:

• North side: Breynat River, Harricana River, Joncas River;
• East side: Harricana River, Joncas River;
• South side: Turgeon River (Eeyou Istchee James Bay), Martigny River;
• West side: Breynat River, Malouin River, Mannerelle River.

The Despreux River derives its source from a forest stream (elevation: 261 metres (856 ft)), located in the municipality of Eeyou Istchee James Bay (municipality).

The source of the Despreux River located at:

• 8.5 kilometres (5.3 mi) West of the Harricana River;
• 15.1 kilometres (9.4 mi) East of the source of the Malouin River;
• 30.5 kilometres (19.0 mi) East of the Ontario border.

From the source, the Despreux River flows over 44.7 kilometres (27.8 mi) according to the following segments:

• 15.4 kilometres (9.6 mi) north, to the dump (coming from the South-East) of Lake Despreux;
• 24.9 kilometres (15.5 mi) to the North, to a creek (coming from the South);
• 4.4 kilometres (2.7 mi) northeasterly to mouth.

The Despreux River flows on the west bank of the Harricana River across the Island of Seven Mile, to:

• 88.6 kilometres (55.1 mi) South-East of the mouth of the Harricana River;
• 26.9 kilometres (16.7 mi) East of the Ontario border;
• 136 kilometres (85 mi) North-West of downtown Matagami, Quebec.

The toponym "Despreux River" was formalized on December 5, 1968, at the Commission de toponymie du Québec, when it was founded.

• List of rivers of Quebec