Essential oils are mixtures of secondary metabolites which can be used as additives for food, cosmetic and pharmaceutical industry. Hydro-distillation technique is one of the most common extraction process but optimization studies are quite uncommon. The present study performed a general mass balance concerning the hydro-distillation of Cymbopogon citratus oil in order to determine the input and output currents. the following solute (leaves)-solvent (water) relationships (g/g) were defined: 50-200; 100-200; 150-200; 200-200; 250-200; 300-200. The greatest amount of oil and the lowest decrease in yield was performed with the following solute/solvent ratio: 200/200 (g/g), obtaining an amount of 1.7 mg of oil and a yield of 1 mg oil/leaves. The present study suggests increasing solute/solvent ratio investigation in order to optimize hydro-destillation process.