The influence of the structure of components of mixed extractants on the partition and separation coefficients was studied for the system: water - ethanol - mixed extractant. Oxygen - containing compounds, which act rather poorly as ethanol extractants, were used in the experiments. The influence of the composition of the extract on the distillation process of water - ethanol - extractant mixtures was also discussed, and a schematic method of manufacturing on oxidation additive for fuels was proposed.