A new particle bounce model has been proposed and compared with the previously published experimental data. By considering the relationship between contact deformation mechanics and contact surface energyit is possible to calculate both the energy required to break the contact surface and the unrecoverable energy contained in the bulk plastic deformation zone when the material yield point is exceeded. Energy spent to deform the local asperities between the contact surfaces was also found to be important when the incident kinetic energy is small. The present model considers the breaking of the contact surfaceplastic deformationand local asperity deformationto be the major energy loss mechanisms during the impaction process. Both the elastic and plastic deformations have been treatedthus making it possible to calculate the coefficient of restitution over a wide range of particle incident speeds.