Water hyacinth available excessively in various water resources can affect ecological system, leading to many public problems. Especially, excessive of water hyacinth bundles could block the floodway leading to the historical flooding of Thailand in 2011. Water hyacinth is a typical lignocellulosic material which is recognized as a potential source of renewable energy. In this present study, hydrothermal treatment on water hyacinth (Eichhornia crassipes) was performed in a temperature range of 160 to 220 ℃ to examine an optimal yield of glucose. After treatment, the product was further hydrolyzed by cellulase. The effect of CH₃COOH as an organic catalyst on liquid composition was experimentally investigated. The liquid fraction was characterized by high performance liquid chromatography (HPLC) using refractive index detector (RID) to analyze the amount of glucose. The solid fraction was also analyzed by United States Department of Agriculture’s method (USDA’s method) to determine the amount of cellulose, hemicellulose, and lignin. The results showed that with the absence of CH₃COOH at 220 ℃, a glucose yield of 26.7% was obtained. Meanwhile, the highest glucose yield of 85.5 % was achieved under the condition of 200℃ with 0.75wt% CH₃COOH and 10wt% water hyacinth intake. A pseudo-first-order kinetic model with regard to cellulose content was developed to explain the conversion mechanism of cellulose to glucose in the hydrothermal treatment process. Based on the estimated rate constants results, this study was in a good agreement with other pervious investigation.