Planar structures metal/alcohol dehydrogenase/metal (Me/ADH/Me), constructed of two technologically symmetrical junctions enzyme/metal and capable to detect ethanol vapour in air after special activation, are investigated. The study is based on original technology of the structures according to which the self-assemblage of the junctions between the metal and enzyme's molecule is affected by controllable electrical current flowing in the colloidal solution and wet precipitated substance until the enzyme layers are completely dried. Surface properties of these Me/ADH/Me structures and their electrical response to ethanol vapour were investigated.