High dependence on fossil fuels to meet the energy demand is the major source of greenhouse gas (GHG) emissions in Thailand. Decarbonization of the energy system to achieve the pledged climate targets is a challenging task for Thailand. The role of green hydrogen and hydrogen-based technologies in Thailand's energy transition needs to be explored. A bottom-up energy system model developed using AIM/Enduse framework has been used to assess the energy system transformation required with the focus on the role of hydrogen in achieving net zero GHG emissions. A business-as-usual (BAU) scenario and two net zero emissions (NZE) scenarios with low and high-hydrogen use have been assessed. This study finds that GHG emission reduction in the power sector and the transport sector would be the major contributor in achieving net zero emission in 2050 compared to the projected emissions in the BAU level. Energy efficiency improvement in the demand side would lower the electricity consumption compared to the BAU level despite the higher electrification of the end-use technologies. However, the demand to produce green hydrogen in the NZE scenarios would increase the electricity generation in 2050 b y up to 54 % compared to the BAU level. The capacity of electrolyser would reach 50 GW by 2050 in the high hydrogen use scenario. This would require additional solar and wind power capacity of 107 GW and 43 GW, respectively. In addition, it would require 50 million cubic meters of water. Cumulative investments in electrolysers to produce green hydrogen and renewable based power generation during 2031–2050 would be USD 122 billion.