Rheinau (German pronunciation: [ˈʁaɪnaʊ]; Low Alemannic: Rhinai) is a city in southwestern Baden-Württemberg, Germany and is part of the district of Ortenau.

Rheinau shares common borders with the following cities and towns, listed clockwise from the north: Lichtenau (district of Rastatt), Achern, Renchen, Appenweier and Kehl (all in the district of Ortenau) and the Alsatian towns of Gambsheim and La Wantzenau.

Rheinau is made up of the boroughs of Freistett (Hauptort and administrative seat of Rheinau with city hall), Diersheim, Hausgereut, Helmlingen, Holzhausen, Honau, Linx, Memprechtshofen and Rheinbischofsheim.

The town of Rheinau was created during the Baden-Württemberg district reform in January 1975 through the combination of the formerly independent municipalities of Freistett, Rheinbischofsheim and Honau.

[3] Rheinau is connected to Achern, Bühl and Kehl by bus lines and belongs to the Public Transportation Authority of the district of Ortenau.