The process of co-gasification of coal and biomass offers the benefits of stable supplies of a primary energy resource - coal, with a partial replacement of a fossil fuel with a "zero-emission", renewable energy source - biomass. The main objective of the experimental steam co-gasification study focused on hydrogen-rich gas generation, as a prospective clean energy carrier, was the determination of the impact of a fuel blend composition and process temperature on the yield and composition of gas generated. The identification of the synergy effects observed in the co-gasification process and their sources was also made with an application of chemometric methods of data analysis, such as the Principal Component Analysis and the Hierarchical Clustering Analysis. Based on the results it was concluded that the synergy effects observed were related to the presence of biomass-derived fuel blends components, such as K2O, Al2O3, Fe2O3, Na2O, TiO2. (C) 2014 Elsevier Ltd. All rights reserved.