Lupeni is a mining city in the Jiu Valley in Hunedoara County, Romania, in the historical region of Transylvania. It is one of the oldest and largest cities in the Jiu Valley. It is located on the banks of the West Jiu river within the Jiu Valley, at a height varying between 630 metres (2,070 ft) (in the east) and 760 metres (2,490 ft). The distance from Lupeni to Petroșani is 18 kilometres (11 mi) (DN66A), and to Deva (the capital of Hunedoara County) is 114 kilometres (71 mi).

The name is derived from the Romanian “lup“, meaning “wolf”. Throughout the second part of the 19th century and most of the 20th century, the city’s economy was based on mining, but since the 1990s the economy has become more diverse, after many mines were closed.