Piezoelectric actuators have found many applications in mechatronics systems because of their ability to provide large forces in very short times. To overcome the limits of the tiny displacements available, different amplification mechanism have been envisaged, namely integration of multiple steps (‘inchworm’), direct mechanical amplification (simple lever, frames) and transfer of impulse to a projectile. Especially in the last two approaches, the dynamic characteristics of the piezoelectric actuator are of primary importance. Manufacturers’ catalogues for commercially available piezo stacks, whilst providing important electrical and basic mechanical compliance data, usually do not give sufficient information on the dynamic behaviour of these devices. This paper provides experimentally observed dynamic performance data for several piezo stacks of differing sizes and from different manufacturers. The observed motion is compared with that predicted by a simple Matlab-Simulink model and suitable model parameters estimated.