Undoped and Aluminium-doped Zinc oxide films have been prepared by thermal evaporation of zinc acetate (Zn(CH3COO)(2). 2H(2)O] and aluminium chloride (AlC3) onto a heated glass substrate. The structural, optical and electrical properties of the films have been studied. The effects of heat treatment for the as-deposited films in air and vacuum are investigated. Over 80% transmittance films with conductivity as low as 2 x 10(-3) Omega cm can be produced by controlling the deposition parameters. The electron carrier densities are in the range 0.2-7 x 10(19) cm(-3) with mobilities of 22-58 cm(2)/ Vs.