Theun Hinboun Power Plant is the first power plant under MDX Public Company Limited and operated by GMS Lao Company Limited (in which GMS Power Public Company Limited holds 100% shares) via Theun Hinboun Power Company Limited, which is a joint-venture of GMS Lao Company Limited holding 20% shares, Electricite Du Laos (EDU) holding 60% shares, and Nordic Hydropower AB holding 20% shares.

Theun Hinboun is a hydropower plant of 210 megawatts as well as the first power plant in Laos operated by an overseas private company for power generation and distribution to Thailand for the term of 30 years (renewable). It is also the first power plant in Laos with the sale agreement with the Electricity Generating Authority of Thailand (EGAT). It was commercially built and came into operation in 1883.

Later, there was an agreement between Theun-Hinboun Power Company and The Government of Lao PDR to allow the company to expand the project to 500 megawatts, leading to the bigger volume to be distributed to EGAT by 440 megawatts, with the remaining 60 megawatts distributed to EDU. There was also the amendment to the distribution agreement of Theun-Hinboun Power Plant and EGAT to accommodate the increased volume.