The air oxidation behaviour of UB2 synthesized via the carbo/borothermic reaction has been investigated using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC), through heating ramp and isothermal studies. Heating ramps from room temperature up to 1173 K showed an on-set of rapid oxidation occurred at a temperature of 807 ± 6 K for samples in fragment form and 799 ± 5 K for finely powdered material. The ramp tests yielded UB2O6 as the ultimate oxidation product. A thermodynamic model for the U-B-O system was used to propose a reaction pathway for the oxidation process in excess oxidiser condition and to predict the amount of heat released. The predictions of the model agreed with the observed phenomena and with the values measured via DSC.