The methodology and results of mass spectrometric studies of the yield of positive ions in the gas phase formed as a result of dissociative ionization of the amino acid molecules of glutamic acid and glutamine by electron impact are described. The experiment was carried out on a setup with a monopoly mass spectrometer of the MX-7304A type in the range of mass numbers 10–150 Da; the mass spectra of these molecules were studied at different temperatures. The features of the processes of formation of ion-fragments of glutamic acid and glutamine molecules by electron impact are analyzed in detail, and the dynamics of the yield of fragment ions in the range of evaporation temperature of the starting material 310–430 K is studied.