In air drying of Eucalyptus urophylla and Corymbia citriodora logs for the production of charcoal it is necessary to be able to predict when logs have reached the required moisture content of ≤ 35%. This study is aimed to produce models using basic density and diameter to predict the moisture content of Eucalyptus urophylla and Corymbia citriodora logs after 30, 60 and 90 days drying. 1,2 m long logs were taken at three different heights from three C. citriodora trees and three trees each from two E. urophylla clones (VM4 and Mn463). The 27 debarked, end sealed logs were air dried under cover for 90 days during which the change in moisture content was monitored. The relationship between density and drying was analyzed by Pearson’s correlation coefficient and the models for predicting the moisture content based on the basic density and diameter were produced. The density and the drying showed a high correlation coefficient. The coefficient of determination of the models was above 0,89 with a standard error lower than 6%. The use of the density and diameter to estimate the wood moisture content simplifies the production of the models, which can be used for Eucalyptus and Corymbia genetic materials.