Aluminium is ranked after iron and steel in the metal market. Aluminium 6061 alloy has been selected by many designers and engineers for different kind of applications. Further, its strength can be improved by cold working, refinement of grains, precipitation and dispersion hardening. In this work, trials are conducted for the investigation of the effects due to age hardening parameters like, solutionizing time, temperature and time for aging on hardness of 6061 Aluminium alloy using Design of Experiments. The response is predicted by using linier regression model. From the results it can be perceived that, the ageing temperature and aging time have a substantial effect on the response whereas, solutionizing time does not have a significant effect. For a specific set of parameters the hardness is improved from 50 to 74 BHN, resulted in an increase in hardness by about 50%.