The coulometric mode of operation is given, if each sample molecule passing the ECD is converted into a negative ion and if each negative ion causes a decrease of the ionization current. The sensitivity of the detector in this case amounts to 96500 C/mol. A hypercoulometric response is given, if fragments from dissociative processes undergo electron capture at several times and if the enhancing effect of space charges is used. In this case the sensitivity of the ECD exceeds the upper limit given by Faraday's number. The operation conditions of both EGD-modes are described.