Magnesium oxalate hollow nanostructures and cobaltous hydroxide nanorods have been synthesized successfully by one-step solid-state chemical reaction at low-heating temperature. Magnesium oxalate hollow nanospheres were obtained via directly grinding magnesium acetate and oxalic acid. Cobaltous hydroxide nanorods were also fabricated by means of a suitable surfactant to modify the solid-state reaction. The as-prepared samples were characterized by X-ray diffraction, TEM, and SEM.