A　scanning　electron　microscope　(SEM),　in　an　oxygen　environment,　was　set-up　to　study　the　charging　phenomena　and　charge　compensation　of　oxides.　Under　an　O-2　pressure　between　2.9　x　10(-3)　and　2　x　10(-2)　Pa,　the　charging　of　an　amorphous　SiO2　with　Cu　stripes　and　a　polycrystalline　Al2O3　were　reduced.　The　charging　effect　and　charge　compensation　of　oxides　may　be　due　to　the　formation　of　surface　anion　vacancies　under　primary　electron　bombardment　and　the　replenishment　of　oxygen　ions　under　an　oxygen　atmosphere.　The　Auger　electron　spectroscopy　(AES)　of　Al2O3　proved　that　the　charging　effect　of　the　Al2O3　was　completely　compensated　in　the　environment　of　O-2　at　pressures　down　to　5　x　10(-6)　Pa.