A new process to produce hydrogen efficiently from sewage sludge (SWS) was developed with cogrinding operation of the dried SWS with calcium and nickel hydroxides (Ca(OH)(2) and Ni(OH)(2)) and subsequent heating of the ground mixture at relatively low temperature below 600 degrees C. A set of analytical methods were used to characterize the ground samples before heating and the gaseous and solid products after heating. Thermo-mass spectroscopic (TG-MS) analysis showed hydrogen occurrence around 450 degrees C. Hydrogen yield over 70 g per kg SWS with concentration of 93.6% was obtained with the hydroxide additions of Ca to C from SWS at 1:1 and Ni to C at 1:6, respectively. X-ray diffraction (XRD) analysis of the solid residues after heating confirmed the existences of calcium carbonate and nickel metal. Based on the obtained results, possible reaction pathway was proposed. (C) 2015 Elsevier Ltd. All rights reserved.