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.
The city lies on the banks of the Western Jiu River within the Jiu Valley, at an elevation varying between 630 metres (2,070 ft) and 760 metres (2,490 ft). It is located 18 kilometres (11 mi) from Petroșani on the DN66A road, and 114 km (71 mi) from Deva.