Metallic conductive ruthenium oxide thin films have been grown epitaxially on sapphire (01 (1) over bar 2) with a cerium oxide buffer layer by pulsed laser deposition. We used transmission electron microscopy, high-resolution electron microscopy, and x-ray diffraction to characterize the growth behavior of the films and the orientation relationship between the films and the substrate. Our electron diffraction and x-ray diffraction studies indicate that the orientation relationships are (200)(RuO2)//(200)(CeO2)//(01 (1) over bar 2)(Al2O3) and [011](RuO2)//[001](CeO2)//[2 (2) over bar 01](Al2O3). All Of the interfaces were seen to be atomically sharp by cross-sectional, high-resolution transmission electron microscopy in the as-grown samples. No precipitates or additional phases were found in the films or at their interfaces.