Particle characterization is a widely used technique in materials science covering such different fields like powder metallurgy, ceramics processing and abrasive-wear applications. Many different parameters can be used to characterize particle size and morphology in powder materials.  Selection of the most suitable parameters depends on the nature of the particles and their specific application. For instance, densification under die compaction is highly dependent on particle roundness. The more spherical the particles, the higher the green density of specimens. Almost all the morphological parameters used to describe three-dimensional shapes can be defined on plane projections, like the images obtained in SEM or OM. A classical non-dimensional parameter to describe particle roundness is P²/A, where P is the perimeter and A is the area of the particle in the plane-projection. Other parameters are the flatness ratio, elongation ratio, bulkiness factor and angularity factor. The aim of this work is to measure the P²/A roundness parameter of two types of particles, one frequently used in abrasive wear tests and the other a raw material used to obtain P/M processed stainless steels.