A study was carried out on leaching of Nigerian kaolin ore by Oxalic acid (C₂H₂O₄.2H₂O). The raw kaolin ore from Share, North central Nigeria was characterised by EDXRF (X-ray fluorescence) and major constituents were SiO₂, Al₂O₃, and minor amounts of K₂O, Na₂O, CaO, TiO₂, along with colour-imparting Fe₂O₃ and MnO that need to be remove to upgrade the kaolin suitability for industrial usages. The effects of parameters such as C₂H₂O₄ concentration, temperature, and particle size were investigated. Under the standard leaching conditions of −75+63 μm particle size, 75 °C and 0.15 mol/L C₂H₂O_4, about 78.5%  of kaolin ore was reacted within 120 minutes. Comparison of the EDX analysis of the raw and leached kaolin showed removal efficiency of 97.1% for the iron at optimal leaching conditions. Energy of activation of 17.65 kJ/mol was obtained in the study supports the proposed diffusion control mechanism for the dissolution process.