We report experimental measurements on the air-water mass transfer characteristics of a pilot pulsed baffled reactor. The experiments have identified, for the first time, the optimal baffle spacing and the optimal superficial gas velocity for mass transfer in the reactor. The mass transfer characteristics were also examined under various operational conditions and were corrected for the effect of temperature and oxygen probe response. The experimental results indicate that the mass transfer rate depends strongly on the combination of the baffle spacing, oscillation frequency and amplitude. The mass transfer data are also correlated in terms of power density and superficial gas velocity, and compared with those from a stirred tank reactor.