The microstructures and aging hardening response of Al-12Zn-3.5Mg-3.0Cu-0.14Zr aluminum alloy after a high-pressure homogenization treatment at 750 degrees C for 45 min under 5 GPa were investigated. The results showed that the constituent phases dissolved completely and formed alpha-Al single-phase solid solution comparable to that formed after ambient-pressure homogenization at 450 degrees C/96 h + 460 degrees C/128 h. The complete dissolution of the constituent phases increased the solubility of the alloying elements, as well with the over-burning temperature and aging hardness.