The effective interfacial area for chemical absorption in a laboratory column has been reported to be a function of liquid viscosity and gas superficial velocity. In this study, liquid viscosity was varied in the range of 0.95 x 10(-3) to 4.5 x 10(-3) Pa s, while gas superficial velocity encompassed the range of 48.0 x 10(-3) to 173.0 x 10(-3) m/s. A transition in the formation of the effective interfacial area was observed and related to the interaction between Liquid viscosity and gas flow conditions. A correlation effectively predicting this transition behavior is developed on the basis of the liquid phase capillary number and the gas phase Reynolds number.