The research in this paper can be separated into two parts. First, the optoelectronic properties of zinc oxide nanowires fabricated by hydrothermal method can be improved by the hydrogen peroxide treatment and the hydrochloric acid (HCl) etching. Zinc oxide (ZnO) nanowires are treated with the hydrogen peroxide (H2O2) solution through two different approaches. The first one is to immerse ZnO nanowires into the H2O2 solution and the samples are heated at 75