We report experimental data of mass transfer of oxygen into yeast re-suspension and yeast culture in a batch pulsed baffled bioreactor and a stirred tank (ST) fermenter. Air bubbles are sparged into the bottom of both reactors and the kinetics of the liquid oxygen concentration followed using dissolved oxygen probes together with the dynamic gassing-out technique for both systems. The k(L)a measurements and correlation with power density calculations for yeast re-suspension show that the k(L)a data in the pulsed baffled bioreactor are on average 75% higher than those obtained in the ST fermenter. Similar trends for k(L)a are also measured when yeast culture of different ages were used in the two systems.