Size distribution of carbon hexagonal planes in carbonized phenolformaldehyde resin and carbonaceous mesophase spherule, which could be recognized as models of coal chars, were evaluated by Diamond's analytical method for XRD patterns. The steepest decent procedure was applied to the convergent process in Diamond's method, and the result was compared to those derived from the image analysis of TEM 002 lattice images of the same samples. Although some deviation probably due to the characteristic difference between XRD measurement and TEM observation, as well as the effect of stacking structure in samples, the average plane sizes decided by both analysis almost coincide with each other. It was accordingly said that the quantitative evaluation of plane size distribution by Diamond's method gave a meaningful result.
