The sol-gel derived aluminum doped ZnO thin films (ZnO: Al) are obtained on coming glass and Si (100) substrates by spin coating technique. As grown films, having optimum level of 0.8 at.% of aluminum doping, show highly preferential c-axis growth. The ZnO:AI films are baked in hydrogen ambient at 350 degrees C for 90 min. The effect on structural, electrical and optical properties of the films with hydrogen incorporation is investigated. The intensity of X-ray diffraction (002) peak, grain size and the conductivity are found to increase after the incorporation of hydrogen. Fourier Transform Infrared results indicate that hydrogen acts as shallow donor. (c) 2005 Elsevier B.V All rights reserved.