For heterogeneously catalyzed multiphase reactions the formation of bubbles may have an influence on the effective reaction rate. This second of a series of two contributions deals with the Ni-catalyzed hydrogenation of hexene, which was used as a model system for an exothermic gas/liquid (G/L) reaction, where gas/vapor bubbles may be generated by overheating of the catalyst. (In part I, results of catalytic H2O2, decomposition were presented, where the evolution of gas bubbles (O-2) always occurs.) A criterion for the formation of vapor bubbles for exothermic G/L reactions is presented, which was verified by experiments in a reactor with an inspection window. For a particle diameter of 6 mm, the effective kinetics of hexene hydrogenation is influenced by internal and external mass and heat transfer. A new and simple method to estimate the mass and heat transfer parameters and the effectiveness factors with regard to pore and external diffusion is presented, which combines the measured temperature difference(s) and the effective rate. For the given reaction conditions, the rate of hexene hydrogenation is not influenced by the evolution of vapor bubbles.