Integrated Gasification Combined Cycle (IGCC) is one of power generation technologies having the highest potential for carbon capture with low penalties in efficiency and cost. Syngas produced by gasification can be decarbonised using chemical looping methods in which an oxygen carrier (usually a metallic oxide) is recycled between the syngas oxidation reactor (fuel reactor) and the chemical agent oxidation reactor (steam reactor). In this way, the resulted carbon dioxide is inherently separated from the other products of combustion and the syngas energy is transferred to an almost pure hydrogen stream suitable to be used not only for power generation but also for transport sector (PEM fuel cells). This paper evaluates in details a chemical looping system, using iron oxides as an oxygen carrier, in conjunction with a co-gasification process of coal and biomass with Carbon Capture and Storage (CCS). The paper assesses from technical point of view the potential application of chemical looping technique for gasification process to generate decarbonised energy vectors (power, hydrogen). Investigated plant concepts with syngas based chemical looping method evaluated in the paper will produce a flexible ratio of power and hydrogen in the range of 400 MW net electricity and 0-200 MW hydrogen. The paper presents in details the plant concept and the methodology used to evaluate the plant performances using critical design factors like: gasifier feeding system (slurry feed vs. transport gas), selection of gasification reactor, heat and power integration analysis, potential ways to increase the overall plant energy efficiency (e.g. integration of air separation unit with gas turbine compressor, steam integration of chemical looping unit into the combined cycle), hydrogen and electricity flexibility analysis, hydrogen and carbon dioxide quality specifications considering the use of hydrogen in transport sector (fuel cells) and carbon dioxide storage in geological formation or using for Enhanced Oil Recovery (EOR). (C) 2010 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved.