A simplified model of the ECD is presented, which is based on the assumption that only a change in the concentration of electron is generating a signal. The model allows to determine four different time constants related to: the collection of electrons (tau(1)), the loss of electrons in the capture process by the impurity molecules (tau(2)), the loss of sample molecules by electron capture (tau(n)) and the removing rate of molecules from the detector volume by the carrier gas (tau(v)). The values of these time constants have been estimated to be in the range of micros for tau(1), ms for tau(2), a part of a second for tau(n) and a few seconds for tau(v). The electron capture efficiency coefficient (p) and the detection coefficient (S(d)) have been defined. These coefficients serve in the model for the coulometric calculation of the mass of analyzed compounds, if the detector works using the conditions described.