The representation of, and reasoning about time play an important role in any intelligent activities. In this paper, we propose an ontology for representing quantitative first order temporal constraints. This logic that we propose in this paper uses instant and interval structures as primitives and has the expressive power of the popular temporal logics of Shoham’s  and BTK’s . The advantage of our logic is that it uses the syntactic structures that explicitly implements the semantics of the temporal structures, such as, true throughout an interval (tt), or true at a point (at). Therefore, developing efficient inference rules and proof procedures for this logic is relatively easy. This paper is organized as the following: In section 2, we introduce the representation of temporal knowledge. In section 3 we introduce our temporal constraint language providing its syntax and semantics. The paper is concluded with a summary and a discussion in section 4.