Ourthe was a department of the First French Empire in present-day Germany and Belgium, at the time written as Ourte by French officials. It was named after the river Ourthe. Its territory corresponded more or less with that of the present-day Belgian province of Liège and a small adjacent region in North Rhine-Westphalia in Germany.
The department was formed when the Southern Netherlands and the left bank of the Rhine were occupied by the French around 1795. Before the occupation, its territory was divided among the bishopric of Liège, the abbacy of Stavelot-Malmedy, the duchies of Limburg, Luxembourg and Brabant, and the county of Namur. Its capital was Liège.
- Liège, cantons: Dalhem, Fléron, Glons, Herve, Hollogne-aux-Pierres, Liège (4 cantons), Louveigné, Seraing and Waremme.
- Huy, cantons: Avennes, Bodegnée, Ferrières, Héron, Huy, Landen and Nandrin.
- Malmedy, cantons: Aubel, Eupen, Kronenburg, Limbourg, Malmedy, Sankt Vith, Schleiden, Spa, Stavelot, Verviers and Vielsalm.
Its population in 1812 was 352,264, and its area was 435,754 hectares.
After Napoleon was defeated in 1814, most of the department became part of the United Kingdom of the Netherlands as the province of Liège. The easternmost part (Eupen, Malmedy, Sankt Vith, Kronenburg, Schleiden) became part of the Prussian Rhine Province; part of this (Eupen, Malmedy and Sankt Vith) was taken back into Liège province after the First World War, under the Treaty of Versailles.