Excessive growth of macroalgae like sea lettuce causes problems in the aquatic environment by creating an anoxic event. Algae have been gaining attention in production of biofuel and other chemical products through biochemical process, which requires drying. In this research, hydrothermal carbonization pro-cess is used for studying the potential utilization of sea lettuce to produce products for application in fuel and agriculture. The reaction was carried out at four temperatures of 150 degrees C, 180 degrees C, 200 degrees C, 220 degrees C for the residence time of 0.5,1 and 2 h. Hydrochar obtained had heating value in the range of 13.4-20.2 MJ kg-1 and higher carbon content as compared to raw sea lettuce. The analysis of the process water showed recovery of nutrients. The co-digestion of process water with food waste at 37 degrees C increased the pro-duction of gas till 10 days. The research showed that sea lettuce is a promising feedstock for hydro thermal carbonization to produce value-added products. (C) 2020 Elsevier Ltd. All rights reserved.