Assesses the potential of petroleum resources in the Thai-Vietnam overlapping area, and evaluates economics of the resources. The Thai-Vietnam overlapping area encompasses southern part of the Pattani Basin and northwestern part of the Malay Basin in the Gulf of thailand between latitudes 7 °35' N, and 8 °05' N and longitudes 101 ํ 55'E and 103 ํ 20'E, and covers 8,470 km2. The area is chosen for study in order to enhance knowledge of geological evolution and hydrocarbon potential of economically important Tertiary strata in the Gulf of Thailand. Using geochemical analyses, source rock potential maps are generated extend and cover the frontier area. It is found that these source rocks are matured, and have adequate both quantity and quality to generate hydrocarbon. Undiscovered petroleum resource is performed using FASPU program for play analysis. Data used in the assessment were derived from its adjacent areas. Results indicate that there is a 75 percent chance of at least to discover 1 gas field with its size of 36.659 BCF, there is a 50 percent chance of at least to discover 1 gas field with its size of 65.606 BCF, there is a 25 percent chance of at least to discover 3 gas fields with their size of 117.409 BCF, and there is an only 5 percent chance of at least to discover 6 gas fields with their size of 271.256 BCF respectively. There is a little chance to discover an oil field in this area as there is a 25 percent chance of at least to discover 1 oil field with its size of 118.052 MMBBL, and there is an only 5 percent chance of at least to discover 2 oil fields with their size of 272.551 MMBBL respectively. As result of economic analysis, the petroleum resource of the Thai-Vietnam overlapping area has sufficient economics potential for further development