CeO2 thin films, an ideal buffer later material for high-temperature superconductors, have been successfully grown on a variety of substrates using pulsed laser ablation. We have been able to control and understand the in-plane epitaxial alignment between CeO2 and the substrates, which in turn led us to prepare high quality epitaxial YBCO films, and, in addition, produce artificial grain boundary by choosing appropriate substrates. The technique holds promise for planar Josephson junction devices.