© 2015 Chiang Mai University. All rights reserved. The objectives of this work, including, produced high concentration hydrogen gas from sugarcane wastes by three-step process, studied the effect of ammonium hydroxide concentration on chemical treatment and studied the effects of milling time in mechanochemical treatment on hydrogen gas concentration in gaseous product and average particle size of milled mixture. The samples were characterized by UV-spectrophotometry, scanning electron microscopy (SEM) with energy dispersive spectrometry (EDS), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), thermogravimetry-mass spectroscopy (TG/MS) and particle size analysis. The gaseous products were analyzed by gas chromatography (GC). The results indicated that the highest lignin content from sugarcane bagasse and sugarcane leaves were 8.1 and 10.4 %w/w when applying of 10 %v/v of ammonium hydroxide. Scanning electron micrograph showed the sugarcane wastes consisted of cell wall and cellulose fibers. The cell wall and cellulose fibers were separated by removing lignin. Furthermore, the EDS analysis showed that the only cell wall of sugarcane wastes consisted of silicon. Hydrogen gas was emitted from the milled sample by heating at about 450-600oC with the low concentrations of methane, carbon monoxide and carbon dioxide. The highest concentration of hydrogen gas was 97 %mol, which was obtained from the milled mixture of sugarcane bagasse/Ni(OH)2/Ca(OH)2 with 120 min of milling time and the lowest concentrations of carbon dioxide below 0.3 %mol. According to, TG/MS and GC results showed that concentration of hydrogen gas increased with an increase in milling time in mechanochemical treatment. Due to the silicon in sugarcane wastes produced calcium silicate (CaSiO3) and carbon dioxide, therefore; the concentration of carbon dioxide collected from sugarcane wastes are higher than from pure cellulose.