The energy sector in the selected Greater Mekong Subregion (GMS) countries, namely Cambodia, Lao PDR, Thailand, and Vietnam, was responsible for around

84% of total CO2 emissions (equivalent to 423.16 MtCO2) in 2015. Without the intervention of climate change mitigation actions, the emissions of CO2 from energy systems would be tremendously increased. Nevertheless, only Thailand appears to have clear targets for reaching carbon neutrality by the mid-21st

century. This study investigates the possibility of energy system transformation to

reach net-zero CO2 emissions in 2050 in the selected nations. The Net-Zero-

Emission (NZE) scenario is built as a CO2 mitigation countermeasure to the

reference scenario. Results show that to reach the goal of decarbonized energy

systems in the NZE scenario, efficient and advanced technologies must be used on

both the demand and supply sides to reduce around 41% of the final energy

demand, and at least 81% of all electricity must be generated by renewable

energy. Additionally, the application of advanced low-carbon technologies,

including carbon capture and storage in the coal, natural gas, and bioenergy

industries and power generation in cooperation with the utilization of electric

vehicles in the transport sector, are the key measures for attaining carbon

neutrality.