The structural and electrical properties of PtRu bimetallic alloy (BA) thin films prepared via atomic layer deposition (ALD) were systemically investigated according to the film composition, which was controlled at a deposition temperature of 340 degrees C by changing the numbers of Pt and Ru subcycles of a supercycle. As-deposited PtRu BA thin films exhibited weaker crystallinity than Pt36Ru64 when the Ru content was high. However, crystallinity improved, and the peak shifts became clearer after Ar heat treatment at 700 degrees C, reflecting the formation of well-mixed solid solutions. The electrical resistivity and work function also improved. The work function of PtRu BA thin films can be controlled between the work functions of Pt and Ru, and is only weakly dependent on the film composition in the single solid solution region.