By electrical resistance tomography (ERT) the cross sectional profiles of gas hold-up in a phi 56mm bubble column are obtained with four designs of gas sparger. The effect of sparger geometry on the bubble distribution is revealed by applying a sensitivity conjugated gradients reconstruction method (SCG). Experimental results show that overall hold-up obtained by ERT is generally in good agreement with those measured with the pressure transducer and the ERT system produces informative evidence that the radial profiles of hold-up is very similar to the sparger design in the lower section of bubble column. Meanwhile, the rise velocity of bubble swarm and the Sauter mean bubble size are evaluated using ERT based on dynamic gas disengagement theory. The experimental results are in good agreement with correlations and conventional estimation obtained using pressure transmitter methods.