Abstract : This study aimed to investigate the optimization of acid gamma-aminobutyric (GABA) content biosynthesis in germinated Mung bean. The effect analysis of soak time, germination temperature, and time on GABA content was using the response surface method (RSM), with a central composite design (CCD) with the support of software JMP version 9.0.2. Results showed that GABA content reaches the highest levels of 3.768± 0.041 mg GABA equivalent/g dry matter as soaking the seeds in tap water. GABA content got the highest value of 4.1006± 0.0326 mg GABA equivalent/g dry matter at the optimization condition (soaking time of 8 hours, germination at 34oC for 26 hours in tap water) and increase of 9.362 times, compared to non-treatment Mung bean seeds. Soaking time, germination time, and germination temperature affected on acid gamma-aminobutyric biosynthesis. GABA is useful for application in the functional food and pharmaceuticals containing GABA.