Transition metal oxides belong to a class of versatile materials that are vitally important for developing new materials with functionality and smartness. Research on manganese oxides has been a key topic among studies on transition metal oxides. This is due to their potential applications in diverse areas, including rechargeable lithium ion batteries, catalysis, molecular adsorption, gas sensors, energy storage, and magnetics. In this review, we will elucidate in detail various characterization strategies, including temperature-dependent growth, micro/nanostructures, Raman, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, and electron spin resonance, for Mn2O3 nanocrystals, highlighting contributions from our laboratory. This review article mainly focuses on the wide-ranging research effort on the development of preparation methodologies and the assessment of various characterization strategies in Mn2O3 nanomaterials. The main purpose is to provide the readers a comprehensive understanding of the research progress of manganese oxides. This is an interdisciplinary work that integrates the areas of physics, chemistry, materials science, and nanotechnology.