Display omitted •Hydrogenation kinetics of limestone under fluidized condition was firstly explored.•MFB-TGA-MS was employed to measure both mass and gas signals simultaneously.•Self-catalytic activity of calcined CaO with 79% CO2 conversion in ICCU-RWGS.•Apparent model of limestone hydrogenation was developed to analyze the kinetics. The integrated CO2 capture and utilization (ICCU) in conjunction with the reverse water–gas shift (RWGS) reaction has emerged as a promising approach to achieve carbon neutrality. However, the scalability of CaCO3 hydrogenation in the context of large volumes of industrial flue gas is impeded by the limited understanding of its performance under fluidized and iso-thermal conditions. This study utilized micro-fluidized bed thermogravimetric analysis coupled with mass spectrometry (MFB-TGA-MS) and in-situ measurements to investigate limestone decomposition under H2 and Ar atmospheres. Results showed that H2 atmosphere increased the limestone decomposition rate by 5-fold (79.1% CO2 conversion and ∼100% CO selectivity at 710 °C) compared to Ar, with RWGS as the dominant route and self-catalytic activity of calcined CaO. Morphology evolution revealed finer pores and textures under H2 conditions. Meanwhile, apparent kinetic models analyzed experimental data and showed a reduction in activation energy from 178.5 kJ/mol (Ar) to 161.3 kJ/mol (H2). These findings support the effectiveness of ICCU-RWGS approaches for further commercialization.