The invention relates to an improved three-way valve structure consisting of a main three-way valve body (1) with inlet (2) and outlet channels (3, 4) that communicate internally by means of an inner obturator element (5) actuated by a key (27), characterized by the relative position of the outlet channels which are perpendicularly arranged in relation to each other and in the same plane perpendicular to the inlet channel, the exterior form of the obturator (5) being a surrounding cylindrical shape and provided with, in the upper part thereof, flanges (9) for the seating of the same and sealing joints (12, 13), ending in a projecting rod (15) with a key seat shape that can fit into the key (27) of the valve. The key enables four functional positions by means of a quarter-circle turn: both outlets open, one outlet open and another closed and both outlets closed.