On behalf of the development of new hydroformylation reactors, a research project was initiated to examine the dynamics of hydroformylation processes. The current paper presents the results of applying the rigorous reactor model (van Elk et al., Chem. Engng. Sci. 45 (1999) 4869¿4879; Chem. Engng. J. 76 (2000) 223¿237) and the approximate reactor model (van Elk et al., 1999) on a new, to be developed, hydroformylation reactor with complex kinetics. The reaction considered is of the first order in the olefin and the catalyst concentration, while the apparent reaction order in hydrogen varies between 0 and 1 and in CO between ¿1 and 1, depending on the hydrogen and carbonmonoxide concentrations, respectively. The influence of the cooler design and the mass transfer on the dynamic behaviour is investigated in the kinetic controlled regime. It is shown that this reactor will show oscillatory behaviour under certain realistic operating conditions. From stability analysis, it was found that the desired steady state (temperature, conversion) exists for a wide range of mass transfer parameters. However, the cases are only statically similar, but dynamically show an important difference: for some conditions, the steady state is found to be dynamically stable, while for others the same steady state is found to be dynamically unstable (limit cycle). This unusual phenomenon is possible due to the negative reaction order in CO.