Introduction: Essential oils are volatile chemical compounds, widely known by their fragrance, as well as by antimicrobial and antioxidant activities. These oils are generally extracted from aromatic plants in procedures using conventional solvents. Methods: In this study, essential oil was extracted from onion (previously chopped and dried) using a mixture of ethanol and CO2 as the extraction fluid. The essential oil obtained from the extraction was collected and purified and the mass was determined (by weighing) to evaluate the effect of CO2 flow on the yield. The essential oil extracted and purified was characterized to determine the acid and refraction indexes, viscosity, and specific mass. Results: The values obtained for refraction and acid indexes are within limits and similar to the average reported in literature. In all cases, when the CO2 was used, there was an increase the essential oil recovery. In terms of quality, the products from this process were characterized to determine the density, acid index and refraction index. The results obtained were similar to those published in the literature. Discussion: The proposed apparatus and CO2 methodology can be considered a good alternative to boost the extraction of essential oil aiming the obtaining of new products for use as raw materials in different industrial processes. Since this apparatus presents more than double extraction yield than Soxhlet experiment.