In this study, the artificial ageing behaviour of 6063 Al-alloy is investigated. A certain part of the aluminium test pieces was solution heat treated (SHT) at 520 degrees C for 2 h, water quenched, then aged at 180 degrees C for 1, 3, 5, 7, 9 and 15 h and the other part was pre-strained for 2 % in tension shortly after the solution heat treatment (SHTP), then aged at 180 degrees C for 1, 3, 5, 7, 9, 15 h in a furnace. Tensile strength, flow stress at 3 %, microhardness and electrical conductivity measurements were employed to investigate the effect of artificial ageing on the mechanical properties of Al-alloy. The variations in ageing time have improved the mechanical properties of the 6063 Al-alloy, whereas the ductility has decreased. The experimental work has revealed that different ageing times at 180 degrees C play a very important role in the precipitation hardening process of the 6063 Al-alloy.