This paper briefly summarizes the results from a project aimed to develop an understanding of oxygen ionic transport processes in highly oriented thin film oxide materials to enable the design of new types of electrolyte materials for solid state electrochemical devices. We have used oxygen-plasma-assisted molecular beam epitaxy (OPA-MBE) to grow highly oriented doped ceria. zriconia thin films on single crystal C-Al2O3 along with multilayered hetero-structures. The influence of dopant concentration, interfaces, defects and crystalline quality on oxygen ionic conductivity has been critically analyzed using various surface and bulk sensitive capabilities. Although, preferred (111) orientation was preserved in high quality samaria doped ceria films up to a 10 atom% Sm doping, the films started to show polycrystalline features for higher Sm doping, Maximum conductivity was obtained for 5 atom% Sm doping in ceria, In the case of gadolinio doped ceria/zirconia multi-layer films, total conductivity was found to increase with the increasing number of layers.