To study the catalytic role of alkali and alkaline earth metallic species and eliminate their negative impact during biomass thermal utilization, different leaching methods have been applied in numerous experiments. Thus it is necessary to investigate the potential influence on biomass physicochemical structure using different agents. Rice straw was selected to study the demineralization impact on physicochemical structure and pyrolysis characteristics. It is shown that strong acid leaching exhibited higher removal efficiency of minerals, but it introduced more notable impact on physicochemical structure of biomass comparing to water and weak acid leaching. Different leaching methods give chance to study catalysis characteristics of intrinsic metals on biomass thermal reaction. Contrast to alkaline earth metals especially Ca hindering thermal decomposition, alkali metals promoted this reaction obviously. In addition, comparing to physicochemical structure changes created by leaching process, the influence of removal of minerals played the dominant role in biomass thermal behavior. (c) 2013 Elsevier Ltd. All rights reserved.