- A single-lever thermostatic mixing valve with priority opening for cold water, then for the distribution of domestic supply water at a given temperature comprising, on the one hand, a body provided with a cold water supply, a hot water supply and an outlet for cold water or water at a given temperature, and, on the other hand, a control lever cooperating with a control rod by means of axial splines, which control rod is arranged axially in a head body, a circlip or retaining ring arranged in a groove of said control rod allowing the latter to be immobilized in translation relative to said head body secured to said body of said mixing valve by a thread of said head body and bearing against an upper face of a cartridge enclosure, another lower face of which bears against the bottom of said body, said lower face including a tubing that engages in the cold water intake so as to allow the admission of cold water directly inside the inner part of said cartridge enclosure, while opposite the hot water intake, a free space is arranged between the bottom of said body and the lower face of said cartridge enclosure to allow the free flow of hot water upward through a chamber arranged around the lower part of said cartridge enclosure, inside which a shoulder is provided that receives a double-sided seat whose lower face is the cold water intake seat and the upper face is the hot water intake seat, a spacer being arranged between the lower face of the head body and the upper face of said seat to guarantee the immobilization of said double-sided seat, a double-sided shuttle being arranged axially in said double-sided seat, the lower face of said shuttle serving as cold water valve opposite the lower face of said seat and the upper face of said shuttle serving as hot water valve opposite the upper face of said seat, a thermodilatable element being arranged inside said shuttle to regulate the temperature of the mixed water, said mixed water, which flows upward in the spacer, being stopped by a valve that comes opposite a mixed water seat or main seat arranged in the upper part of said spacer, said valve being carried by a valve holder that cooperates with the control rod and inside which a spring is arranged, one end of which bears inside said valve holder and the other end of which bears on an adjusting sleeve sliding in said valve holder cooperating with said shuttle such that: - in an opening direction of the mixing valve using the lever, in a first phase, the valve is opened simultaneously with the cold water intake seat, owing to the bearing of said spring, while the hot water intake seat is closed by the hot water valve to make it possible to obtain cold water without any contribution of hot water then, in a second phase, the hot water seat is gradually opened while reducing the cold water passage, and - in an opposite direction, during the closing of the mixing valve using the lever, in a first phase, the hot water seat is gradually closed while increasing the passage of cold water in order to close the hot water, then, in a second phase, the valve is closed in order to close the cold water. - in an opening direction of the mixing valve using the lever, in a first phase, the valve is opened simultaneously with the cold water intake seat, owing to the bearing of said spring, while the hot water intake seat is closed by the hot water valve to make it possible to obtain cold water without any contribution of hot water then, in a second phase, the hot water seat is gradually opened while reducing the cold water passage, and - in an opposite direction, during the closing of the mixing valve using the lever, in a first phase, the hot water seat is gradually closed while increasing the passage of cold water in order to close the hot water, then, in a second phase, the valve is closed in order to close the cold water.