<Venturi aeration> is a promising technique, where <air aspiration>, <bubble generation> and the bioreaction content stirring are performed in a very simple compact piece of equipment. It is applicable especially in <biological effluent> treatment and <emergency aeration> of natural water reservoirs. In the paper a model of <mass transfer> in clean water for Venturi aeration in thanks od scale from 0.5 to 400 cubic meters is presented. The model has the form of a correlation of volumetric mass transfer coefficient with total energy consumption per liquid volume and superficial air velocity. The efficiency problem of the aerator on the basis of the author's definitions of oxygenation rate and oxygenate efficiency is discussed.