Phenolic compound from Nephelium lappaceum leaves was investigated using Gallic acid as a precursor. The compound was extracted from the leaves in 50, 70, 90 and 100 methanol solvent (10:1 w/v ratio) at 60ͦC and 75ͦC. Based on HPLC analyses, the optimum of 71.4 mg/g of GA was extracted from green leaves in 50 methanol at 60ͦC with FRAP value of 0.23 mM/500 mg. FRAP result showed that the effect of metal chelating activity was significantly increased with increasing extract concentration and GA was the dominant phytochemicals in the NL giving significant antioxidant activity. © 2014 Trans Tech Publications, Switzerland.