Abstract: The determination of interfacial area in a packed column by the "chemical method" has been studied with absorpton of pure CO2 in carbonate buffer solutions in the presence of AsO2- or C1O- catalyst respectively. The mass transfer data were treated by means of the Danckwerts surface renewal model and the modified surface film renewal model, and then compared. It was shown that the specific interfacial area "a" calculated with these two models were very close to each other, while the values of the renewal frequency "S" seemed to be quite different. The average difference of the values of "a" measured with the two catalysts AsO2- and C1O- was +(9.2-15.5)%. In the modified model the transient mass transfer and reaction during the initial gas-liquid contact were considered, and it was proposed that k1θ>2 might be taken as a criterion to determine the gas-liquid interfacial area by the "chemical method", so that the range of value of k1 for absorption systems could be predicted.It could thus be considered that values obtained by the ClO- catalyst system when determining "a" and "S" were more correct. Moreover, experiments on physical absorption were carried out with the CO2-Na2SO4 system in the same packed column, and the results were correlated with the chemical absorption data. It can be concluded that the modified model seems to be more reasonable for analyzing the operating characteristics of gas-liquid absorption in a packed column.