The integration of User Centered Design (UCD) and agile methodologies for software development is suitable to achieve software products with higher degree of usability. However there are few controlled experiments that can show the advantages and the approach of this integration. The present paper describes the whole process of integrate one of the popular agile methodologies, Extreme Programming (XP), with UCD applied to the construction of a software application. The project deals with a mobile application about the vegetation from Pontificia Universidad Católica del Perú that allows users to search, recognize and find plants around the university campus.