In this paper, we consider the morphological development and intrinsic reactivity or two microporous carbon chars burning at conditions typical of a pulverized-fuel combustor (i.e., particle temperatures above 1300 K. and diameters below 200 μm). The model chars were chosen for their low ash and volatile matter contents to preclude the complicating effects of these components on the oxidation process. The partially oxidized samples (0 to 65% mass loss), which were collected in an entrained-flow reactor, are experimentally characterized by their total surface area, particle diameter, apparent density. pore volume distribution, and macroporous surface area. SEM photomicrographs of the external particle surface and refiected-light photomicrographs of the internal porosity of the particles are also presented. These measurements demonstrate that combustion occurs under Zone II conditions.