Experimental mass transfer data and literature data of airlift loop reactors are analyzed concerning the effect of the gas phase residence time on the volumetric mass transfer coefficient k(L)a. It becomes evident that a neglect of the oxygen depletion can be regarded as a diminishment of the mass transfer driving force. The latter is found to be an important cause of the mass transfer dependency on the actual apparatus height of airlift loop reactors. Therefore, a new correlation is presented that describes the volumetric mass transfer coefficients of airlift loop reactors by including the effect of gas phase transient component concentration depletion.