The article deals with the simultaneous application of the classical penetration theory to both oblate ellipsoidal and spherical-cap bubbles coexisting in the heterogeneous (churn-turbulent) regime of bubble column operation. The theoretical volumetric liquid-phase mass transfer coefficients, k(L)a (referred to dispersion volume), for both small and large bubbles were first calculated by means of the classical penetration theory and then corrected due to the nonspherical bubble shape. The correction procedure developed by Nedeltchev et al. [1-3] has been successfully applied. Two new correction factors, f(oe)(het) (for the small ellipsoidal bubbles) and f(sc)(het) (for the large spherical-cap bubbles), were introduced. f(oe)(het) was correlated to the Eotvos number. Eo, whereas f(sc)(het) was correlated to the constant large bubble aspect ratio. For the verification of this concept, k(L)a values in 15 different organic liquids and 7 preadjusted liquid mixtures were used (see Ozturk et al. [4]). The overall k(L)a values were estimated as a sum of both k(L)a values for the small (oblate ellipsoidal) bubbles and k(L)a values for the large (spherical-cap) bubbles. Each theoretical k(L)a value was multiplied by the corresponding correction term. As many as 102 experimental k(L)a values were predicted successfully with an average relative error of 7.1%.