The liquid of the green coconut shell (GCS), an effluent stream from the industrial processing of green coconut rind, is rich in sugars and is a suitable feedstock for fermentation. The purposes of this study were to optimize the production of ethanol using GCS synthetic as a basis for fermentation and to compare with real GCS. Fermentation was carried out in bench-scale bioreactors using Saccharomyces cerevisiae as inoculum, at a working volume of 5 L and using 0.30% of soy oil as antifoam. During fermentations, the effects of different initial sugars concentrations (10 - 20%), yeast concentrations (5 and 7.5%), temperatures (30 - 50°C) and agitation rates (400 and 500 rpm) on pH/sugars profiles and ethanol production were evaluated. The best conditions for ethanol conversion were (1) media containing 15% of sugar; (2) 7.5% yeast inoculum; (3) temperature set point of 40°C and (4) an agitation rate of 500 rpm, which resulted in an ethanol conversion rate of 98% after 6 hours of process. The conditions optimized with synthetic medium demonstrated to be a good model for work with GCS.