The motion characteristics of conjunct bubbles rising in stagnant glycerol-water solutions were investigated for Morton numbers in the range 1.072 x 10(-2) 58.48. It was found that the terminal rise velocities of the conjunct bubbles were similar to those for single bubbles with the same spherical-equivalent diameters. The rise velocity was quantified on the basis of the standard expression for the drag coefficient and the projected area of the leading bubble, where the projected area diameter was found to be a function of the diameter ratio of the leading and trailing bubbles and for Reynolds numbers greater than 1. Mobility of the gas-liquid interface was also included in the analysis. Good agreement was obtained between the measured and predicted rise velocity over the range of Morton numbers investigated. Particle image velocimetry was used to quantify the liquid velocity flow field around the interacting bubbles during the formation and stabilization stages of the conjunction bubble. The similarities to and differences from those for a single rising bubble were discussed.