Mg–Zn thin film alloys were produced by thermal co-evaporation using single source and dual source geometries. The films containing high amount of Zn (66 at.%) were prone to formation of metallic micro spheres on the surface when high evaporation rates (10 nm s−1) were used. The Mg–27.1 at.% Zn bulk alloy was found to be suitable for co-deposition with Al for producing Al–Mg–Zn thin film alloys. A low Al concentration gradient (5 at.%) could be obtained along the sample due to the high deposition rates of Mg–Zn (7.5 nm s−1) combined with low Al deposition rates (0.2 nm s−1). The Al–Mg–Zn thin films showed an improved resistance against chemical attack when higher amounts of Al are used, as shown by downstream analytics investigations using a flat flow electrochemical cell coupled to an AAS system.