This study presents bioconversion of water hyacinth (Eichhornia crassipes) to bioethanol using two-sequential steps of acid hydrolysis (10% sulfuric acid) and yeast (Candida intermedia) fermentation. A maximum ethanol yield (coefficient, 0.21 g g-1; productivity, 0.010 g l-1h-1) was comparable to predicted value (0.23 g g-1) obtained by CCD (Central Composite Design). Two colorimetric methods (phloroglucinol and dichromate assays) were used for determination of xylose and ethanol using UV-Vis spectrophotometer.