Hollandite-type MnO2 (HMDO) with hydronium as tunnel counter ion was synthesized by oxidation of MnSO4 with ozone in a concentrated sulfuric acid solution.Its composition and structure were analyzed and characterized by inductive coupled plasma atomic emission spectrometry (ICP-AES), titration, Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD) and scanning electron microscopy (SEM).Hydronium can be exchanged with hydrated lithium ion and the exchanged HMDO can be dehydrated at 300°C. Cyclic voltammetry and galvanostatic charge–discharge study showed that HMDO with lithium ion exchanged and dehydrated had potential to be used as a cathode material in lithium secondary batteries.