In this paper, the experimental evaluation of velocity and residence time of single bubbles of different sizes in a gassed oscillatory baffled column (OBC) using a high-speed imaging technique is reported. This work is particularly concentrated on the effect of oscillatory amplitude. The results show that the instantaneous axial bubble velocities vary up to four times with respect to the mean value at an oscillatory amplitude greater than 2 mm. The ratio of the radial to axial bubble velocity increases beyond unity for the highest oscillation amplitude investigated. The direct measurement of residence time of the bubbles within a baffled cell is also reported. (C) 2003 Society of Chemical Industry.