In this work, the magnetic and electronic properties of the mineral hausmannite (Mn3O4) have been studied using both experimental and theoretical methods. Magnetic susceptibility χ was measured in the paramagnetic region over the temperature range of 288–1000 K using the Faraday method. The anomalies recorded at 657 K and 898 K in the χ⁻¹(T) plots were attributed to the Jahn–Teller effect, and this phenomenon was also found in the differential scanning calorimetry (DSC) analysis. Using the first-principles calculations based on the DFT+U method within the Quantum ESPRESSO package, the magnetic moment values of –4.1113 and 3.4801 Bohr magnetons (μB) for Mn2+ and Mn3+ ions, respectively, were obtained. The result of a net magnetization of 6.00 μB per cell was established which indicated the ferrimagnetic nature of the object. Band structure analysis confirmed the semiconductor nature of hausmannite (a theoretical band gap Eg ≈ 0,82 eV).