Peel oil of Citrus nobilis (Lour) was analyzed for determining its chemical composition. Fourteen identified components accounted for 99.1% (GC) and 100.0% (FID) of the total oil. Major component of the oil was limonene (76.8%-GC and 86.2%-FID). Essential oil was also evaluated for its antioxidant activity in four complementary test systems namely; beta-carotene/linoleic acid, DPPH radical scavenging, reducing power and metal chelating activities. In the first system, antioxidant activity increased with the increasing concentration. At 20.0 mg.ml(-1) concentration, antioxidant property of the oil was 96.8% +/- 0.2 and as strong as the positive controls BHT and alpha-tocopherol. Scavenging effect of the oil was superior to the positive controls BHT and alpha-tocopherol at 1.5 mg.ml(-1) concentration (96.4% +/- 0.1). Reducing power and chelating effect of the essential oil increased with the increasing concentration.