A research program was conducted to characterize the grain size distribution and shape characteristics of indigenous, discontinuous SiC and Al₂O₃ materials as possible ceramic reinforcements for PCMMCs. The results from automatic image analysis prove that a simple aspect ratio (maximum to minimum size ratio) is not able to completely define the required morphology of reinforcements, ranging in size between 1 and 10 mm. More complex shape factors were introduced with additional effect determined on three geometrical features of the particle: surface area, perimeter and maximal dimension. Alumina (Al₂O₃) with higher roundness shape factors appears to be beneficial especially for the applications where ductility is an important requirement.