A quantitative experimental program, to determine the effects of small surface waves on interfacial mass transfer was undertaken. In addition, pertinent mass transfer and hydrodynamic theory is presented and discussed. The particular scheme explored is that of transfer from the gas phase into a liquid (absorption), with water as the liquid throughout all experiments. The substances absorbed were Oxygen, Helium, Carbon Dioxide and Propylene. They were present as essentially pure gases. Small amplitude, progressive two dimensional waves were mechanically generated at the liquid surface. For each system, control experiments with non-waved surfaces were also carried out. Unsteady state runs were made and total gas absorbed was measured with time. (Author)