Savannakhet (ສະຫວັນນະເຂດ), officially named Kaysone Phomvihane (Lao: ໄກສອນ ພົມວິຫານ; Thai: ไกสอน พมวิหาน) since 2005 and previously known as Khanthaboury (ຄັນທະບູລີ), is a city in western Laos. It is the capital of Savannakhet Province. With a population of 125,760 (2018), it is the second-largest city in Laos, after Vientiane. Although the old French colonial quarter of the town, along the Mekong River-front, is depressed and crumbling, the town's proximity to Thailand's booming economy has brought about new commercial development in the northern part of the town, near both the river crossing and the bus terminal.
Like all Lao cities, Savannakhet has a mixed population of Lao, Thai, Vietnamese and Chinese, as well as minority peoples from the Lao interior. It has a large 15th-century Buddhist temple, Wat Sainyaphum, a Chinese temple, the Catholic Co-Cathedral of St. Therese and a mosque.