Abstract: In a method and apparatus of an amperometric probe for characterization of the electrostatic state in gases containing ions, by means of the electrical space potential and/or the density of positive and negative ions, in particular in gases flowing around a sensor (1) with an applied electrical potential (5, 6), and emitting ions to the sensor; an electrical circuit (2) is provided for detecting the measured sensor curents; a current comparison unit (3) follows the current detection and monitors that the sensor currents are within the permissible value range in terms of their mathematical sign and their magnitude, applies a first sensor potential and detects the associated sensor current, as well as subsequently applies a second sensor potential and carries out an adaptation process in such a way that the detected second sensor current has the same mathematical sign as the first sensor current; the space potential and the density of the ions of one polarity are determined in a calculation unit (4); and, with