The gas phase reaction between BrNO and O-3 at low pressure (<10 mbar) results in the formation of BrNO2 in about 60% yield. In this manner N-15- and O-18-labeled BrNO2 are prepared. In addition, it is shown that BrNO2 also forms by the heterogeneous low-temperature reaction between gaseous BrNO and solid sulfuric acid, doped with H2O2. It can be assumed that BrNO2 may be formed in a similar way under stratospheric conditions. The isotope scrambling in the reaction between BrNO and O-18(3) as well as in the gas phase equilibrium BrNO + NO2 reversible arrow BrNO2 + NO are investigated. For the equilibrium constant a lower limit of K-298 greater than or equal to 1 x 10(-3) is deduced from infrared measurements. A detailed IR and Raman study on BrNO2 is performed. Photolysis of matrix-isolated BrNO2 at different wavelengths leads to a mixture of cis- and trans-BrONO. The vibrational data of BrNO2 (6 fundamentals, 7 combinations), cis-BrONO (5 fundamentals, 1 overtone), and trans-BrONO (4 fundamentals, 8 combinations) as well as the calculated force fields are in excellent agreement with the ab initio values, predicted by T. J. Lee (J. Phys. Chem. 1996, 100, 19847).