Novel measurement systems are applied to characterize external surface area, volume, and drag coefficient/ mass (Cd/m) ratios of two sized coal fractions and a sample of carbon spheres. Measurements are made on individual particles with nominal diameters ranging from 75 to 150 t~m. The measurement system incorporates an electrodynamic balance, to isolate particles, with video-based and high-speed diode array imaging systems for particle characterization. Accurate estimates of the Stoke's drag are obtained for the coal particles by applying a general solution method developed for slightly deformed spheres. Analysis methods are developed using shape and drag information to calculate mass and density distributions for the two coals studied. Results of these measurements and analyses are validated by independent mass measurements using a particle weighing and counting technique. For the coals studied surface area equivalent particle diameters range from 4% to 20% higher than the corresponding volume equivalent particle diameters. Particle densities ranged from 1.01 to 1.34 g/cm 3 for a 23 particle sample set of Pittsburgh seam hva bituminous coal and from 0.81 to 1.38 g/cm 3 for a 30-particle sample set of New Mexico subbituminous coal. From a combustion perspective, the results presented indicate that particle sphere assumptions employed in most combustion models can lead to significant errors (20%-25% on average for the samples studied) in calculated particle volume and associated thermal mass. Particle-to-particle density variations indicate that even if surface area and volume differences are adequately handled in a heat transfer analysis, large uncertainties result in particle temperature response due to particle property variations. The measurement and analysis techniques presented are capable of providing the detailed particle property data required for developing improved combustion models.