In this paper we investigated the interaction between emotional and non-emotional aspects of persuasion dialogues, from the viewpoint of both the system (the Persuader), when reasoning on the persuasion attempt, and the user (the Receiver), when reacting to it. We are working on an Embodied Conversational Agent (ECA) which applies natural argumentation techniques to persuade users to improve their behaviour in the healthy eating domain. The ECA observes the user’s attitude during the dialogue, so as to select an appropriate persuasion strategy or to respond intelligently to user’s reactions to suggestions received. We grounded our work on the analysis of two corpora: a corpus of ‘natural’ persuasion examples and a corpus of user’s reactions to persuasion attempts.