The energy distribution functions of electrons are obtained by analysing thick-target Bremsstrahlung spectra. The method consists of expanding the unknown function on an appropriate functions basis and of solving the resulting system of linear equations. The various atomic processes involved can be treated with the desired accuracy. Applications are given for a variety of cases such as hollow cathode discharge plasmas, hot magnetized plasmas, and electron beams of travelling wave tubes. The analysis includes cases when the thick target is covered by an impurity coat.