Organic wastes from Swiettenia marcophylla L, Artocarpus heterophyllus L, Mangifera indica L, and Annona muricata L were prepared by grinding into 0.1875, 0.3750, 0.7500 mm of particle size and delignified by 2% NaOH at 80oC for 90 minutes. Acid dilution hydrolysis process with H2SO4 1% was performed at 150oC for 120 minutes in a closed reactor. The effect of particle size and delignification on and reducing sugar concentration were investigated. The result showed (1) leaves that can be used as raw material to produce hydrogen should have 38– 49% cellulose and hemicellulose. (2) Reducing sugar concentration increased with particle size reduction and delignification. (3) the best result with the highest reducing sugar concentration was achieved by 0.1875 mm particle size with delignification on Annona muricata L.