This work presents an informational web application aimed to encour- age smokers to consider quitting smoking. This website incorporates two avatars, a man and a woman. The user interacts with one of them by is- suing voice commands. The design of the web-app was informed by a user study conducted with ex-smokers. The aim of the study was to under- stand the contents of the web, the language in which the avatars should speak and the way in which these avatars should be designed. Once the development of the application was nished, a series of tests with users was carried out, to evaluate the impact of the web-app on their views about quitting smoking. This study allowed us to validate the impact of the avatar on the user's decision to consider quitting smoking.