In this study, a group of Ni-Co/Mg-Al catalysts was prepared for hydrogen production via supercritical water gasification of lignin. The effects of different supports and preparation methods were examined. All catalysts were evaluated under the operation conditions of 650 degrees C, 26 MPa, and water to biomass mass ratio of 5 in a batch reactor. The Cop. 2.6Ni-5.2Co/2.6Mg-Al catalyst showed the best performance with highest gas yield (12.9 wt%) and hydrogen yield (2.36 mmol . g(-1)). The results from catalyst characterization suggest that the properties of this type of catalyst are dependent on multiple factors including support Mg-Al molar ratio and preparation method, and better coke resistance of the catalyst could be obtained by the preparation method of coprecipitation. Therefore, coprecipitation method should be applied for the preparation of Ni-Co/Mg-Al catalysts for hydrogen production via supercritical water gasification of lignin. Copyright (C) 2017 John Wiley & Sons, Ltd.