Supercritical water gasification (SCWG) of sugarcane bagasse was performed to produce hydrogen. The process was manipulated with nano-catalysts to make it highly selective for hydrogen production. Copper based catalysts impregnated on gamma-Al2O3 were tested to find the best Cu percentage. The catalyst was promoted with different percentages of potassium. Catalysts were characterized using different techniques. They were used in SCWG to find effect of potassium on hydrogen selectivity. Results showed remarkable role for K on improvement of hydrogen selectivity. Addition of 2.5 wt.% of potassium increased H-2 selectivity from 0.76 to 1.17 with no significant decrease in total hydrogen production. The catalysts were characterized using ICP, XRD, TPR, BET and TEM techniques. Bagasse feedstock elemental structure was analyzed using CHNS technique. (C) Copyright 2015, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.