The biological reduction of bromate (BrO₃^-) in a hydrogen based membrane biofilm reactor (MBfR) was investigated to determine if bromate could be reduced below the MCL of 10 µg/L, and the inhibitory impacts of nitrate and bromate concentration on bromate reduction. Reduction of bromate to below the 10 µg/L MCL was achieved with an influent nitrate concentration of 5 mgN/L and influent bromate concentrations ranging from 150 µg/L to 1,500 µg/L. Pseudo-steady state experiments were conducted to examine the influence of nitrate and bromate on bromate reduction. Nitrate was shown to inhibit bromate reduction at concentrations as low as 0.5 mgN/L. Bromate reduction followed Monod-type kinetics, with increased bromate reduction being achieved until an effluent bromate of 15 mg/L was reached. Over an extended period of exposure to bromate concentrations greater than 15 mg/L, bromate appeared to exhibit an inhibitory effect on bromate reduction. The production of bromite, an intermediate of bromate reduction, may be responsible for this inhibition. Includes 15 references, table, figures.