In this paper, our work is devoted to systematic study of actions theories by using a logical formalism based on a first order language increased by operators whose main is to facilitate the representation of causal and temporal relationships between actions and their effects as well as causal and temporal relationships between actions and events. In Allen and Mc-Dermott’ formalisms, we notice that notions of past, present and future do not appear in the predicate Ecause. How to affirm that effects don’t precede causes? To use the concept of temporality without limiting themselves to intervals, we enrich our language by an operator defined on time-elements Our formalism avoids an ambiguity like: effect precedes cause. The originality of this work lies in proposal for a formalism based on equivalence classes. We also defined an operator who allows us to represent the evolutions of the universe for various futures and pasts. These operators allow to represent the types of reasoning which are prediction, explanation and planning. we propose a new ontology for causal and temporal representation of actions/events. The ontology used in our formalism consists of facts, events, process, causality, action and planning.