Particle dampers offer considerable potential for suppressing structural resonant conditions over a wide frequency range compared with tuned mass dampers or tuned vibration absorbers. However, they exhibit phenomenological behaviour such as fluidisation which relates to the motion of the particles that in turn is dependent on the excitation level. This paper describes some experimental results of the damping characteristics of particle damping devices and presents a prediction model for the damping characteristics which clearly show that the damping levels are dependent on the geometry of the device and the resulting motion of the particles arising from the level of the input excitation.