The hydro-distilled essential oil of Syzygium aromaticum was diluted for analysis to 0.5% in HPLC-grade n-hexane and then injected into a GC -MS apparatus. Gas chromatographyelectron impact mass spectrometry (GC-EIMS) analyses were performed with an Agilent 7890B gas chromatograph equipped with an Agilent HP-5MS coupled with an Agilent 5977B single quadrupole mass detector. Capillary column (30m×0.25 mm; coating thickness 0.25μm) was used. Analytical conditions were as follows: injector and transfer line temperatures 220 and 240 °C, respectively; oven temperature programmed from 60 to 240 °C at 3 °C/min; carrier gas helium at 1 ml/min; injection of 1μl (0.5% HPLC grade n-hexane solution); split ratio 1:25. The acquisition parameters were as follows: full scan; scan range: 30-300 m/z; scan time: 1.0 sec. The individual components of the essential oil of S. aromaticum were identified based on a comparison of the retention times with those of the authentic samples, comparing their linear retention indices relative to the series of n-hydrocarbons. Computer matching was also used against commercial (NIST 14 and ADAMS) and laboratory-developed mass spectra library built up from pure substances and components of known oils and MS literature data .