The spatial liquid-phase concentrations were measured by means of an electrical conductivity probe in a 0.289-m ID bubble column operated at superficial gas velocities (u(g)) of 0.018, 0.031 and 0.038 m/s, respectively. The column was equipped with a perforated plate gas distributor (0.002 mo x 31 holes). Carbon dioxide was used as a tracer gas, whereas deionized water was used as a liquid phase. The local liquid-phase axial dispersion coefficient E-L was derived from the local liquid-phase concentrations by means of the graphical method developed by Khang and Kothari (1980). It was found that the spatial distribution of the local E-L coefficients becomes radially non-uniform as a function of u(g). At the regime transition velocity (U-trans = 0.031 m/s) between bubbly and transition flow regimes the mean, E-L coefficient for the upper zone (UZ) becomes identical to the one for the lower zone (LZ). At both lower and higher u(g) values E-L(UZ) is systematically higher than E-L(LZ). The same result also holds if the overall bubble bed (BB) is divided into core and annulus regions. It was proven that, in the bubbly flow regime (u(g) < U-trans), E-L (core region) approximate to E-L (annulus region), whereas in the transition flow regime (u(g) > U-trans), E-L (annulus region) > E-L (core region). The effect of the aerated liquid height L on the spatial distribution of the local E-L coefficients was studied, as well. Three different BBs, viz. L = 0.64 m (shallow BB), 1.28 m (medium BB) and 2.1 m (deep BB) were examined at u(g) = 0.038 m/s. The spatial distribution of the local E-L coefficients was most scattered in the shallow BB (L = 0.64 m). In a medium BB with an aerated liquid height L = 1.28 m the existence of a well-developed helical flow structure was detected. It was shown that the graphically determined mean E-L coefficient (for the overall BB) increases as a function of both the superficial gas velocity u(g) and aerated liquid height L, and a useful empirical correlation was derived. It covers the following range of bed aspect ratios: 2.1 less than or equal to L/D-c less than or equal to 7.3.