Effect of pottassium and sodium application on the wood characteristics of Eucalyptus grandis W. Hill, at 24 months old-trees. The present work had as objective to evaluate the wood anatomical characteristics and the wood apparent and basic density of Eucalyptus grandis 24 months old-trees, planted in the spacing of 3x2 m, without fertilization (control) and fertilized with potassium (T2) and sodium (T3). For each treatment they cut 8 eucalyptus trees, acoording to basal area distribution, and collected wood samples at different percentages of tree heights. In the evaluation of the vessel and fiber dimensions and the wood apparent density by X- ray densitometry they were used wood samples at DBH and for wood basic density they were used all the wood samples. The results showed that the apparent and basic wood density values were not significant in the 3 treatments, and the radial wood density profiles were characteristic of juvenile wood of eucalyptus trees. The application of mineral fertilizers (potassium and sodium) induced alterations in the fiber dimensions, responsible for the eucalypt tree sustentation and not significant differences for the vessels elements were detected.