This work investigated roles of an perforated plate on the gas-liquid mass transfer in an airlift contactor (ALC), and it was found that the effect of the perforated plate was twofold. Firstly, it helped in breaking up large bubbles that passed through the plate. It was observed that inserting a perforated plate could increase the interfacial area between gas and liquid to more than twice its original value. Secondly, the presence of a perforated plate seemed to lower down the mass transfer coefficient between the two phases. The analysis showed that the effect of the increase in the interfacial area between gas and liquid exceeded that of the reduction in the mass transfer coefficient. Hence, the overall rate of gas-liquid mass transfer in the employed ALC was found to be enhanced when perforated plates were inserted into the system. The effect of the configuration of perforated plate, i.e. hole size, number of hole, and the number of perforated plate, was also investigated.