ZnO:Al films were deposited by reactive d.c. magnetron co-sputtering from two separate metallic targets of Zn and Al in an Ar/O-2 atmosphere. A first study of the Al incorporation, of the film morphology, of the electrical and optical properties was carried out considering the most relevant deposition parameters, the dissipation power P-Al of the Al source and the oxygen flow rate f(O-2). The Al concentration in the films was found to increase with increasing P-Al and to decrease with increasing f(O-2). The films exhibited a textured columnar structure within a well defined range of P-Al and f(O-2) where the optimum for high optical transmission and low resistivity was also observed.