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TM/Landsat 5 images (April and May 2009) from Capão Bonito (SP) region where Eucalyptus urophilla, Eucalyptus grandis and a hybrid of both species have been planted were utilized in the spectral characterization of some stands that presented structural differences explained mainly by age. These images have been converted to physical values such as surface reflectance factors and from these values principal components images were generated. The dispersion of PC1 and PC2 on a bi-dimensional space has been evaluated to identify tendencies of pixels positioning. Results have shown that for young eucalyptus canopies (up to 3 years old) the positioning is well defined, occupying the lower part of the dispersion clouds and far from the graph origin (zero). This result indicates more participation of the lower portions of the canopies, which presents lower values of reflectance in the near infrared (bare soil or dry branches) and high reflectance in the visible region. The older canopies presented higher influence of photosynthetic active leaves rather than the shadowed and lower portions of the canopies. The spectral characterization of eucalyptus canopies at the two temporal set of data was consistent.