A novel gas solid Micro Fluidized Bed Reaction Analyzer (MFBRA) was developed to deduce reaction rates and kinetic parameters through measuring time-dependent composition changes of evolved gases from the reactions. Application of the MFBRA to the decomposition of CaCO3 powder resulted in an apparent activation energy of 142.73 kJ/mol and a pre-exponential factor of 399,777 s(-1). This apparent activation energy was much lower than the thermogravimetry-measured value of 184.31 kJ/mol, demonstrating a quicker reaction in the MFBRA. This was further verified by CuO reduction in CO, as accelerated by the fast diffusion and high heating rate in the MFBRA. Measurement of pyrolysis of coal and biomass in MFBRA found that the reaction process was completed in about 10 s, a time much shorter than the literature-reported values in larger fluidized bed reactors. By monitoring the release of gas species from reactions at different temperatures, the MFBRA also allowed deeper insight into the mechanism of pyrolysis reactions. (C) 2010 American Institute of Chemical Engineers AIChE J, 56: 2905-2912, 2010