Seven coal samples taken from cores drilled in the Cretaceous Mannville Group were used for investigation of coal properties and carbon dioxide (CO2) gasification. The depths of the cores ranged between 700 and 800 m below the surface in the Western Canadian Sedimentary Basin. A new method was developed with an average heating rate of 200 K/min using CO2 as the gasifying agent from the experiment's beginning until its end. The coal properties of the seven coals from these deep coal seams showed certain similarities and variations. There is an obvious relationship between the reactivity and the material properties determined in the study. In particular, the specific surface area calculated relative to the carbon content measured in the ultimate analysis showed a correlation with the reactivity. The ash content and composition also appeared to influence char reactivity. The gasification behaviors of the in situ coals were compared to those of two surface-mined coals. The new method of coal gasification showed a significant difference to those that were heated up in an inert gas, such as nitrogen, to the target temperature. A maximum rate of reaction did not exist when the new method was used, and the integrated core model gave better results than the commonly used random pore model in terms of kinetic modeling.