ABSTRACTThe crystal structure and magnetic properties in epitaxially grown Sr1-xBaxRuO3 on SrTiO3 substrates were determined. Epitaxial Sr1-xBaxRuO3 exhibits a simple perovskite structure in the whole region of Ba/Sr ratio, in contrast to a complex hexagonal layered perovskite in the case of Ba-rich bulk Sr1-xBaxRuO3 which has plane-sharing oxygen octahedra. Tetragonal deformation was enhanced from the pseudo cubic structure of SrRuO3 to a highly distorted tetragonal lattice in BaRu03. Electronic properties such as conductivity and magnetization were examined and compared to the results of band calculation in which a tetragonal distortion was taken into account. A metal-insulator transition was not observed in this system either in the experiment or in the simulation, and metallic conductivity was maintained in the whole region of Ba content. The ferromagnetic ordering which occurs at 160K in pseudo-cubic bulk SrRuO3 was suppressed in Sr1-xBaxRuO3 films with increasing tetragonal deformation and Curie temperature decreased to 50K in BaRuO3.