Manganese oxide nanoflowers were synthesized by a simple hydrothermal method at 150 degrees C and 170 degrees C temperature using potassium permanganate (0.1 M and 0.3 M) as manganese source and cetyltrimethylammonium bromide (0.05 M) as size reducing reagent. A reaction duration of 12 h was used in all the experiments. The synthesized product consists of the mixed phases of cubic Mn2O3 and orthorhombic Mn3O4 systems as analyzed from X-ray diffraction studies. Fourier transform infrared spectroscopic studies confirmed the presence of Mn-O bond. High resolution transmission electron microscopic images show the formation of nanoflower structures. The average diameter of the nanoflowers is similar to 771 nm. The influence of reaction temperature and molar concentration of potassium permanganate on the morphology of manganese oxide was studied by field emission scanning electron microscopy. (C) 2018 Elsevier B.V. All rights reserved.