A device for sensing the electrical conductivity of a liquid, particularly that of the washing bath in a washing machine, including an electrically insulating supporting casing through which first and second electrodes intended to contact the washing bath extend to the outside, electrical power supply and signal acquisition and processing circuit devices housed at least in part in the supporting casing and coupled to the electrodes, and signal coupling and galvanic isolation devices, interposed between these circuit devices and the electrodes and also housed in the casing, and including at least a first and a second capacitor, each of which is interconnected in series between one of the electrodes and a corresponding terminal of the circuit.