The validation of conceptual models is an important task with the aim of checking whether the model correctly and adequately expresses the requirements informally stated by the users. Different techniques and tools have been developed to support this task. In this paper and as part of a doctoral work, we propose an animation tool for an object oriented modelling language. This tool generates executable specifications from conceptual model specifications on the same level of abstraction. In this way, the model behaviour can be observed and checked against the intended requirements. We introduce the modelling language, the functionalities of the animation system and its architecture.