Abstract: The mechanism and kinetics of hydroformylation of propene under low pressure have been studied, pseudo-first-order equations were derived, and rate constants, activation engery and optimum contact time for producing butyl aldehyde have been calculated. Next, the influence of reactor diameter on absorption efficiency, mass transfer coefficient, axial mixing of liquid and average bubble diameter were examined. The result shows an obvious effect of bubble diameter on propene conversion. Hence bubble diameter should be used as a significant factor for reactor scale-up. A mathematical model based on experiments of hydroformylation of propene in a packed bubble reactor is as follows: where the coefficient of contact efficiency M can be obtained from a three-region model.