In this study, hardness and densification behaviour of aluminium, iron and alumina powders after Cold Isostatic Pressing (CIP) were examined. For this purpose, a cold isostatic pressing unit was designed and constructed. Using this pressure unit, aluminium, iron, and ceramic powders have been pressed and then their hardness and densification behaviours were investigated. Pressed densities were about 98% for aluminium, 88% for iron and 50% for alumina powders after CIP. Pressing resulted with significant increases in microhardness values of iron and aluminium powders. Scanning electron microscopy (SEM) examinations revealed that severe plastic deformations took place on the aluminium and iron powder particles, and no plastic deformation was observed in alumina powders.