A mixer valve device, in particular for mixing hot and cold water, has a movable shutter that adjusts the flow of hot water and of cold water into a mixing chamber so as to have in the outlet mixed hot/cold water at a given preset temperature; the device combines a gearmotor and a thermostat; during the step of setting the device the gearmotor moves the shutter to the position substantially corresponding to the required temperature of the mixed water; the thermostat maintains the required temperature within a preset tolerance by moving the shutter correspondingly. A mixer valve device is thus made that has reduced mechanical wear and low electric consumption and is safe and reliable.