Abstract: The influence of preparation conditions, such as pyrolysis temperature and feed moisture content, on the combustion reactivity of chars produced from spruce wood by the flash pyrolysis has been investigated using a thermogravimetric analyser (TGA). The chars were produced in a fluidised bed reactor at 748 K, 773 K and 823 K, and with wood feed containing different moisture contents of 0, 7.0% and 11.3%. It was found that the reactivity of a char in chemical kinetic control regime increased with decreasing pyrolysis temperature, and the volatile matter (VM) content and H/C ratio in chars also increased with decreasing pyrolysis temperature. There may have a direct relationship between the reactivity of chars and the combination of VM and H/C. In addition, chars produced under lower pyrolysis temperature possess higher activation energy and are more sensitive to combustion temperature, compared with those produced under higher pyrolysis temperature. It was found that feed moisture content has only a minor influence on char reactivity but has a significant effect on the volatile material content of chars produced at higher pyrolysis temperatures. Finally, a simple power-law kinetic model that has been employed to properly describe the char combustion.