A total of 11 structured packirigs with surface areas (a(p)) from 125 to 500 m(2)/m(3) and corrugation-angles (theta) from 45 to 70 degrees were studied to explore the effects of the packing geometry on mass transfer. A new concept, the mixing point density, was proposed to represent the effects of a(p) and theta. A generalized method to calculate the mixing point density from a(p) and theta was developed. Dimensionless mass-transfer models are developed, to predict the effective area, liquid-film, and gas:film mass-transfer coefficients, with the mixing and Reynolds numbers imbedded into the correlations. Compared with literature models, the models developed in this work capture the effects of the packing geometry and predict the mass-transfer properties in aqueous systems.