In this paper, hydrothermal carbonization (HTC) is applied to oil palm shells to produce a solid fuel known as hydrochar. The effect of reaction temperatures 220-290 degrees C at reaction time 30min, and a biomass to water ratio of 0.15g/g (15wt%) was investigated for synthesis of hydrochar. The hydrochar yield percentage decreased from 62.4 to 43% with increasing temperature from 220 to 290 degrees C-. In addition, carbon percentage increased with an increase in temperature from 26.93 (oil palm shell) to 63.77% (hydrochar produced at 290 degrees C). The higher heating value (HHV) tended to increase from 12.24MJ/kg (oil palm shell) to 26.80MJ/kg for hydrochar products. The raw palm shell and hydrochars were characterized using Fourier Transform Infrared (FTIR), Branuer-Emmett-Teller (BET), Field Emission Electron Microscopy (FESEM), and thermogravimetric analysis (TGA). Surface porosity of hydrochar product increased, which resulted in a compacted surface and large surface area. BET surface area, total pore volume, and average pore diameter were improved from 0.316m(2)/g, 0.00129cm(3)/g, and 45.1153nm to 12.5996m(2)/g, 0.0557cm(3)/g, and 113.4120nm, respectively, at 260 degrees C-..