Results of SANS and USANS measurements performed on a series of six vitrinite samples having vitrinite reflectance (R-0) values ranging from 0.55% (high volatile bituminous rank) to 1.28% (medium volatile bituminous rank) were analyzed. Experimental data were acquired for two sample forms: platelets cut parallel to the bedding and pellets made up of randomly oriented, nearly-monodisperse particles. Numerical analysis indicates the presence of sub-micron sized inclusions embedded in the organic matrix. For the lowest-rank vitrinites, the dominating inclusions are monodisperse are similar to 7-12 nm in diameter, and have concentrations of the order of 10(17) cm(-3). Their shape is anisotropic, with the surface-to-volume ratio about three times larger than for a solid sphere. The higher-rank vitrinites contain much larger monodisperse inclusions having diameters of similar to 50 nm, concentrations of similar to 10(14) cm(-3), large surface-to-volume ratios, and fuzzy interfaces with the organic matrix. Inclusions of a similar size and concentration are also present in the lowest-rank sample, but are much less frequent than the small inclusions. We provisionally interpret those objects as inclusions of mineral matter, most likely associated with original plant material. The internal specific surface area (SSA) calculated for the small mineral matter inclusions is similar to 100 m(2)/cm(3) and for the large inclusions similar to 2 m(2)/cm(3).