Turbulence measurements carried out in a vessel, in which turbulence was produced by means of upflowing microjets of water, with zero mean shear stress at the interface, show that the turbulent kinetic energy level is increased close to the interface where horizontal eddies develop. Gas absorption experiments carried out simultaneously show that the interfacial turbulence level and the gas absorption coefficient are closely related. In the same conditions, velocity power density spectra show a development of the lower frequencies in the horizontal direction. When a surfactant (Hexadecanol) is added, interfacial mass transfer is reduced while the existing horizontal velocity fluctuations are relatively damped. There. the interface behaves more like a solid wall than like a free surface.