Mixing intensity, gas hold-up and volumetric mass transfer coefficient are presented for multiple-impeller configurations of two types of impellers: Pitched Blade impeller, which pumps the liquid upwards, and Narcissus impeller. Transport characteristics were measured in a vessel of inner diameter 0.29 m. Oxygen was used as the gas phase and the liquid phase was 0.5 M solution of Na2SO4, which results in non-coalescing bubbles. Gas hold-up and volumetric mass transfer coefficients are presented for individual impeller configurations as a function of power consumption and superficial gas velocity. The results are compared with transport characteristics measured for other impeller types previously. The comparison of transport characteristics of Pitched Blade impeller pumping up and Narcissus impeller points on higher mixing intensities of Pitched Blade impeller, while Narcissus impeller provides higher volumetric mass transfer coefficient. (C) 2004 Elsevier B.V. All rights reserved.