A simplified approach to the model development and scale-up of a packed bubble column reactor from pilot semi-batch mode to continuous commercial operation has been presented. This is illustrated by choosing the reaction of ethynylation of formaldehyde to 1,4-butynediol for which correct reaction mechanism is difficult to postulate in the compelling safety limitations. The apparent reaction kinetics has been determined from the semi-batch pilot data for previous catalyst charges. The true kinetics has been predicted taking into account the gas-liquid, liquid-solid mass transfer and axial dispersion effects and has been expressed as a function of catalyst loading, temperature and ＇age＇ of the catalyst. The actual conversion from the commercial reactor system was found to match the model prediction reasonably well.