An expaimental study has been aimed at Linking the extent of axial mixing m gas and liquid phas~ m tall bubble coltmm reactors with the respective bubbling regimes (homogeneous, tr~msition, hctcrogeneous) ¢ncotmtered in such reactors and with correnpondhag macro-scale flow patterns of b~h phases. The expc~-imental progamme, carried out m a bubble column reactor of 0.14 m in diameter and 4.1 m in height, included determination of gas and liquid phase residence time distribution (RTD) characteri~ics for different modes of primary gas dispersion and flow visualisation experiments aimed at idmtification of macro-scale flow pattmas in the reactor. The experimental rezults proved an ~tial effect of gas diapevAon mode (bubbLing regime) on the extent of gas :rod liquid phase mixing in the reactor. The respective dependences of Peo and Pex on the superficial gas velocity, obtained with the diaaSbuting plate gmcratmg sequentially homogeneous, tran.sition and heterogeneous bubbling regimen, indicated very sensitively the transition from the homogeneous to the heterogeneous bubbling mode (the onset of the trmasition bubbling regime) occtmmg at u,o = 0.04 m s "l with the appearance of local macroeddien in the bed. The compmason of our mixing data with correaponding dependences of gas holdup and kLaL on the superficial gas velocity revealed the existence of direct links between the variations of RTD and mass transfer characteristics induced by the changes of gas dispersion (bubbling) mode. The results of the analysis of variances of gas phase RTD curves justified (in algcxaneat with corresponding Peo data) the plug flow approximation for the gas phase in the homogeneous bubbling regtme and indicated the convective mechanism of gas mixing within the whole region of heterogeneous bubbling conditions. Analogically, the data for the liquid phase yielded the convective mechmai,ma of liquid mixing within the whole range of experimental conditions. The mixing data obtained for both phases in the heterogeneous bubbling regmxe were adequately described by the model of consecutive circulation ceils with the bae&flow between adjacamt cells, proposed on the basis of the flow visualisation experiments as a realistic sampllfied represontation of the macro-scale flow structures in heterogeneous bubble beds.