The adoption of the concept of reactive (fusible) and inert (infusible) macerals in pulverized fuel (p.f.) combustion is examined together with the need to determine these constituents under realistic conditions. A laser microreactor method is described in which 100 μm monomaceral particles are heated at 105 - 106 K s -1 to ~1600 °C in air. Two applications are described. First, the particles are heated for ~40 ms, the pyrolysis converting the maceral into a char particle with individual morphology; in particular, whether the maceral fuses or melts (termed reactive) or not (termed inert) is determined by optical microscopy. Second, high-speed cinephotomicroscopy of the combusting particle is possible using longer irradiation periods, revealing in great detail the morphology of swelling and combustion. The validity of the method is substantiated by comparing char morphologies with those from a drop-tube furnace. Other features of the laser microreactor technique are discussed and it is shown that the equipment simulates the p.f. combustion process properly for these applications.