This paper explores Thailand’s partial liberalization of the electricity industry and to what extent is a Foreign Direct Investment (FDI) allowed in the electricity sector. As Thailand is an ASEAN Member State, the paper aims to review whether the partial liberalization under the ESB model is consistent with the commitments of the ASEAN. The paper examines both the ACIA and the AFAS, and it finds that Thailand has no commitment under both agreements relevant to entry of a FDI in its electricity sector. However, Thailand already allows the entry of a FDI in the power generation business which is aligned with the principles of market access and National Treatment that fulfill the obligations under the ACIA and the AFAS in case Thailand will make any commitments in the future. It is noted that electricity transmissions and the distribution and supply businesses are still prohibited for both Thai and foreign investors.