The oxidative bromination of C-2-C-8 alkenes with HBr-NaNO2-O-2 in solutions of BMImBr, HMImBr or BMImBF(4) containing 16-28 wt% H2O was studied using volumetric method, GC-MS analysis, N-14 NMR and UV-VIS spectroscopy. The optimal conditions to conduct the reaction at high selectivity for 1,2-dibromoalkanes in BMImBr were determined. The composition of ionic liquid affects the catalytic performance. Although in BMImBF(4) the reaction runs with equal rate as in bromide ionic liquid, the fraction of bromohydrin in the reaction products increases to 20 %. Generated from NaNO2, NOx operated as a catalyst in the oxidation of Br- and was oxidized to catalytically inert NO3 (-) anions when complete conversion of HBr was attained. Oxidative bromination of alkenes.