Although the logic developed by William of Ockham is regarded as having considerable interest, both from a historical and from a philosophical point of view, little attention has been paid to the temporal aspects of his doctrines. This creates a barrier to the full understanding of Ockham´s logic because it leads to many controversies that are due to partial interpretations which underestimate the role of time in the logic of the Middle Ages. In the present study, the temporal character of Ockham´s logic is analyzed in order to contextualize it within his general theories. The first part of our investigation is concerned with the basic notions of Ockham´s logic, and the second part studies their interaction with temporal notions. It becomes clear that Ockham´s logic is essentially temporal. This is mainly due to the fact that it concentrates on the analysis of the latin language, and that the doctrine of temporal propositions and of temporal syllogism are based on a conception of supposition that must be able to deal with a broad conception of signification. The domain of objects signified includes what is, or what could be, in the present as well as in the past and in the future. This shows that fundamental notions of Ockham´s logic presuppose the temporal character of ordinary language.