Using a free fall apparatus, the coefficient of restitution and the contact time of steel spheres at impact on thin gold-coated glass plates were measured experimentally. The influence of the impact velocity, the particle size, and the plate thickness has been investigated. The measurements were evaluated using the Zener model. However, since the model merely considers energy dissipation due to elastic flexural waves and ignores additional energy dissipation by friction and viscous damping, the experimental values remain slightly below the theoretical Zener curve.