High crystalline manganese oxides with birnessite-type (H-BirMO) and large 2×4 tunnel-type (Na-2×4) were synthesized simultaneously using a low crystalline Na-form birnessite (NaBir) as a precursor in a 2 M NaOH solution at low temperature (150 °C) and autogenous pressure. The weight ratio of the obtained Na-2×4 to H-BirMO was about 50. Elemental analyses indicated that Na-2×4 had a formula in one unit cell of Na 8 Mn 27 O 53 ·9H 2 O, and the manganese average oxidation state was 3.63. H-BirMO had a formula of Na 0.31 Mn 2.04 O 4 ·0.66H 2 O and the manganese average oxidation state of 3.77. H-BirMO contained a set of basal reflections with d values that correspond to a minimum periodicity along c equal to 7.06 Å. H-BirMO belonged to a monoclinic system, and the lattice parameters were a=5.18 Å, b=2.85 Å, c=7.35 Å, and β=103.3°, respectively. Na-2×4 showed that the first peak appeared at a d spacing of 12.07 Å in the [0 0 2] direction, and the second peak had a similar d spacing of 7.16 Å in the [2 0 0] direction with Na-birnessite in the [1 0 0] direction. FE-SEM image of H-BirMO showed a very large plate-like morphology, while SEM photograph of Na-2×4 consisted of nanofibers with a thickness of about 80 nm and lengths ranging between 6 and 10 μm.