The water distillated essential oil of Citruslimon collected from Ramsar, Province of Mazandaran, North of Iran collected in December 2013, was analyzed using gas chromatography (GC) and gas chromatography-mass spectroscopy (GC-MS). The yield of oil was 0.23% w/w. Twenty-one components representing 100% of the essential oil were characterized. Limonene (61.4%), b-pinene (13.1%) and g-terpinene (11.3%) were identified as the main constituents in the volatile oil. The antioxidant ability of the oil was examined by free radical scavenging method using 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical at different concentration of the oil. The Citruslimon oil exhibited free-radical-scavenging properties with IC50 value of 284.71µg ml -1 .