Volumetric oxygen mass transfer coefficient (k(L)a) in an airlift reactor with internal loop (working volume of 40 dm(3)) was studied experimentally in the water batch. The k(L)a values were measured using both the dynamic pressure-step method (DPM) proposed by Linek and gassing-out method (GOM), the standard variation. The k(L)a values obtained by the DPM were not dependent on the concentration of oxygen in the inlet gas and by about 15% higher than those obtained by the GOM. Based on our observations, empirical parameter values in the correlation between k(L)a and gas holdup, proposed by Bello, were changed to new values.