Bamboo is a plants that is easily found almost everywhere and it has big potential as a renewable energy source after proper treatment. This study discusses the processing of bamboo waste biomass into solid biofuel by hydrothermal treatment. This treatment directly processes biomass with high moisture content without prior drying treatment. Hydrothermal treatment applies thermal disintegration of biomass in high-pressure hot water. Hot water acts as reactant as well as catalyst to convert biomass into hydrochar. The experiment was conducted using an autoclave reactor with a capacity of 250 ml. The operating condition was set at temperature of 240 and 300°C, initial pressure of 1.0 Mpa with biomass/water (b/w) ratio variations of of 1:20; 2:20 and 3:20. Meanwhile residence time was set to be 30 minutes. Samples were characterized in terms of solid yield, proximate analysis, ultimate analysis and calorific value. The experiment results showed that approximately 42 - 87 wt % of the biomass feed was recovered after treatment as the solid product. It was also found that increasing temperature and b / w ratio was very influential on the amount heating value of the solid product. Hence,the highest heating value of the solid product (5309 cal/g) was obtained at process with temperature of 300°C and b/w ratio of 2:20.