The velocity of air bubbles in Newtonian liquids moving due to centrifugal forces in a centrifuge was investigated. The comparison of experimental results with a model in which free bubble surface was assumed, reveals that within the range of dimensionless diameters defined by Eq. (2) acid smaller than 2, the bubble surface hardens during the motion which results in a velocity decrease. A comparison of the results with relationships determining the motion induced by gravity forces shows that the Bond criterion which describes transition from the rigid to free surface state can be generalized to the field of the centrifugal forces.