A model and implementation process of a conversational rational agent as a kernel of a dialogue system and/or as an element (agent) of a multiagent system including definition of a conceptual architecture of a conversational rational agent; formal specification of the different components of this architecture and their combination permitting a formal model to be obtained; definition of the software architecture implementing the formal architecture; and definition of implementation mechanisms of the formal specifications, the rational agent being suited both to converse with another agent or with a user of the system through any communication medium.