The values of the plasmon energies generated by X-ray excited Auger electrons from the L3M4,5M4,5 lines from selenium have been measured for the binary glasses GeSe2 and GeSe3.5 as 17·7 and 18·0 eV respectively. Measurements have also been made on glasses with ternary additions of either gallium, antimony or bismuth. For the glasses containing different concentrations of bismuth it is found that the plasmon energy does not alter from 17.5 eV, even though the conductivity is reported to change from p- to n-type. For the other glasses containing gallium or antimony there is a reduction of the value of the plasmon energy as the selenium content of the glass is reduced. The value of the plasmon-loss energy for germanium in GeSe2has been measured as 15.7 eV which is different to the value for selenium and evidence is presented to show that the glass may be composed of medium-range ordered units. The change of ionicity from ionic to covalent is calculated for the selenium-germanium bond on the addition of antimony.