This investigation describes and analyses the experimental results pertinent to the penetration of steel plates of 20, 40 and 80 mm thickness by non-deforming, ogive shaped 20 mm diameter projectiles over the velocity range 300-800 m/s. All the tests were carried out at normal impact angle, i.e. zero obliquity. The experimental results presented include the variation of the depth of penetration, crater volume, lip height, bulge height and diameter and specific energy absorption capacity with impact velocity in 20, 40 and 80 mm plates. Selected data on the size and shape of the plastic zone in the plate surrounding the penetrating projectile have also been obtained. These experimental data have been rationalized on the basis of energy based models: one for constrained, plane strain penetration and the other for bulging characterized by unconstrained, plane stress plastic flow. © 1992 Pergamon Press Ltd.