Stoichiometric local characterizations of YBaCuO oxides have been performed using a 1.4 MeV deuteron microbeam. A beam with a size of 10 15 μm 2 allows the observation of variations of x = 0.2 in sintered YBa 2 Cu 3 O 7 - x . Local variations of oxygen stoichiometry in a melt-textured sample, correlated with the microstructure, have been observed. In spite of the degradation of the sample under the beam, oxygen measurements seem to remain significant for doses above 10 1 8 ions/cm 2 .