A novel γ-MnO₂ hollow structure has been synthesized at room temperature using a simple chemical reaction between MnSO₄ and KMnO₄ in aqueous solution without using any templates, surfactants, catalysts, calcination and hydrothermal processes. The synthesized γ-MnO₂ hollow structure was characterized by x-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and BET analysis. It was found that the hollow structure consisting of short γ-MnO₂ nanorods with diameters of 5–10 nm and lengths of 50–100 nm could form when the MnSO₄/KMnO₄ mole ratio was equal to or larger than 2.3. The excess amount of Mn²⁺ in solution was observed to promote the crystallization of γ-MnO₂ nanorods and the formation of the γ-MnO₂ hollow structure. In addition, the evolution of microstructure and morphology of the products obtained with a MnSO₄/KMnO₄ mole ratio of 2.3 at different reaction times revealed that the hollow structure was formed via an Ostward ripening process. Furthermore, the obtained γ-MnO₂ hollow structure was found to exhibit a better catalytic performance than conventional γ-MnO₂ in the aerobic oxidation of benzyl alcohol to benzaldehyde, demonstrating its possible application in alcohol oxidation.