The Psou (/psoʊ/; Adyghe: Псыу; Georgian: ფსოუ; Abkhaz: Ԥсоу; Russian: Псоу) is a river in the West Caucasus, bordering the Gagra Range to the east.

It flows along the southern slopes of the Greater Caucasus Mountain Range and forms a part of the border between Georgia (Abkhazia[1]) and Russia.

Between 1913 and 1955 there was a hydrological station in operation at Leselidze, roughly 1.5 kilometres (0.93 mi) upstream of the river mouth.

[2] The Psou gained notoriety as a smuggling route out of the country, by-passing Russian controls on the border.

[4][5] As of 2008 it was still designated as a transboundary river which lacked an international cooperation agreement as part of the UNECE Water Convention.