Abstract: Capacitative device for measuring the moisture content of granular or powder materials, particularly materials in motion on a conveyor belt or in a pipe comprising a capacitative probe provided with at least two electrodes separated by an insulating zone and in contact with the material being examined, a support frame for the capacitative probe, and high frequency oscillator circuit associated with the electrodes in order to supply an alternating voltage of a frequency variable with the moisture content. The probe, which has a cylindrical body may be rotated by a motor and comprises cleaning scrapers mounted on the frame which cooperate with the body of the probe when the latter is rotating.