The volatiles of a commercial sample of Cinnamomum cassia (Nees and T. Nees) J. Presl. essential oil were analyzed by gas chromatography-mass spectrometry (GC-MS). The identification of the components was confirmed by Kovats retention index and their quantities were established using internal standard. These analyses had led to the identification of 72 chemicals and quantification of 41 of them. The majority of volatiles identified belongs to oxygenated compounds (e.g., aldehydes) while non oxygenated terpenes represent about 18% of the oil. The odor quality of cassia essential oil was assessed by Gas Chromatography-Olfactometry (GC-O). Among the 26 components identified with GC-O, AEDA (Aroma Extract Dilution Analysis) has allowed to establish a number of components with high dilution factor (strongly odorous) such as cinnamaldehyde, 3-phenylpropanal, guaiacol and 2-phenylethanol.