The bubble column reactor (BCR) used in Part I was subjected to forced oscillations at high gas rates under jetting conditions. Two piston types were used: a flexible rubber membrane as used in Part I and a modification thereof to cause a more rigid, stiff piston behavior. The mass transfer performance differences between the piston types were quite remarkable, the former yielding peaking with respect to increased frequency and the latter produced monotonic increases up to an asymptote as the frequency was increased. The Benjamin-Ursell stability theory was found useful in tracking regimes of maximum enhancement. (c) 2005 American Institute of Chemical Engineers.