Abstract : The multimedia field exists since a long time, but its importance is increased by the convergence of industries such as movies, telecommunications or video games. Multimedia content is based on monomedia contents and defines various aspects whose main ones are spatial and temporel compositions. Within this scope, we propose the language TAO (Temporal Algebraic Operators) which allows to define multimedia presentations. TAO is an object-oriented language where objects make reference to monomedia data. Temporal operators specify the composition of these objects, according to a semantics defined with the notion of interval. The language temporal model is based on interval temporel points and causal relations expressing their links. The semantics of TAO programs is given by a normalization process and some of their properties are analysed, as equality and stop. We also present an execution engine for TAO programs which we implemented in Java by reusing an existing prototype. It is based on a set of sequential instructions and jumps. TAO programs are compiled into contexts of instructions which are managed by the various components of the execution engine.