Al doped ZnO nanoparticles of about 40 nm in diameter were prepared by hydrothermal method. The phase and the morphology of the above nanoparticles were investigated by using SEM and XRD. The UV-VIS absorption and transmittance of the fabricated ZnO. Al thin films were studied; also the films electrical resistivity was measured. A low electrical resistivity of about 0.12 Ω cm and transmittance of about 85% were obtained.