We reported herein the synthesis in high yields ( > 97%) of Ce0.9Sm0.1O2-delta nanowires displaying well-defined shape, size, and composition by a simple, fast, and low-cost two-step hydrothermal method. The Ce0.9Sm0.1O2-delta nanowires synthesis was followed by the wet impregnation of Ni without the utilization of any stabilizing agent. The Ni/Ce0.9Sm0.1O2-delta nanowires showed higher surface area, high concentration of oxygen vacancies at surface, and finely dispersed Ni particles with significantly higher metallic surface area as compared with catalysts prepared from commercial materials with similar compositions. Such unique and improved properties are reflected on the catalytic performance of the Ni/Ce0.9Sm0.1O2-delta nanowires towards ethanol steam reforming. The nanowires exhibited high yields for hydrogen production (similar to 60% of selectivity) and an exceptional stability with no loss of activity after 192 h of reaction at 550 degrees C. The reported results provide insights and can inspire high-yield production of nanostructured catalysts displaying controlled and superior properties that enable practical applications in heterogeneous catalysis.