Material Point Method is used to study the impact deformation of elastic-perfectly plastic spherical particles. A wide range of material properties, i.e. density, Young's modulus and yield strength, are considered. The method is particularly suitable for simulating extensive deformation. The focus of the analysis is on linking the coefficient of restitution and the percentage of the incident kinetic energy dissipated by plastic deformation, W p /W i × 100, to the material properties and impact conditions. Dimensionless groups which unify the data for the full range of material properties have been identified for this purpose. The results show that when the particle deforms extensively, W p /W i × 100 and the equivalent plastic strain, are only dependent on the particle yield strength and the incident kinetic energy, as intuitively expected. On the other hand, when the deformation is small, Young's modulus of the particle also affects both W p /W i × 100 and the equivalent plastic strain. Moreover, coefficient of restitution is insensitive to Young's modulus of the material. Dimensionless correlations are then suggested for prediction of the coefficient of restitution, the equivalent plastic strain and W p /W i × 100. Finally, it is shown that the extent to which the particle flattens due to impact can be predicted using its yield strength and initial kinetic energy.