Supercritical fluid extraction (SFE) of essential oils from commercial cinnamon bark was compared with essential oils that were obtained by hydrodistillation. Effects of operating parameters (pressure, temperature and extraction time of SFE) on the extraction yield and the composition of the extracted volatile oil were studied. Moreover, in the hydrodistillation process, the effect of the pH of the solvent on the concentration of cinnamaldehyde in the extracted volatile oil was studied. The maximum yield of extract in the SFE process is about 7.8% at 70 degrees C and 240 bar. The maximum concentration of cinnamaldehyde in the SFE process was obtained at 70 degrees C and 160 bar, and the maximum concentration of this component in hydrodistillation was achieved at pH = 4.1.