The CO2 gasification reactions of biomass char in granulated BFS (blast furnace slag) were isothermally investigated using a thermogravimetric analyzer with the temperature ranging from 1173 K to 1323 K. The effects of temperature, biomass type and granulated BFS on the kinetic characterizations of CO2 gasification of biomass char were illuminated. The kinetic mechanism models and parameters were obtained through a novel two-step calculation method. The results indicated that the CO2 gasification reactivity of biomass char as conversion and gasification index increased with the increase of temperature and it could be promoted through granulated BFS. The CO2 gasification reactivity of CS (cornstalk) char with lower alkali index was lower than that of PS (peanut shell) char. The A(4) model (Avrami-Erofeev (m = 4) model) and A(3) model (Avrami-Erofeev (m = 3) model) were demonstrated as the best appropriate models for CO2 gasification of CS char and PS char, respectively. The gasification activation energy of CS char ranging from 155.08 to 160.48 kJ/mol was higher than that of PS char whether with or without granulated BFS. Granulated BFS could decrease the activation energy of CO2 gasification of char at any biomass type. (C) 2018 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.