Trials have been carried out with Holm oak and Cork oak acorns, in the same edafoclimatic conditions in land in Extremadura, in order to establish germination losses by growth temperatures and loss of humidity. The results show that temperature does not affect germination until it rises above 55º C, therefore it does not have a negative effect, whatever the type of storage. In Holm oak, the loss of humidity of 15 p. 100 brings about a mayor decrease in the germination, which is absolute from 20 p. 100. In the Cork oak, there is an acceptable level of germination between a loss of 25-30 p. 100 and nil germination from 40 p. 100. With the drying of the air, under trial conditions, the Holm oak acorns did not germinate after 21 days, and the Cork oak after 38 days.