The temporal organization of discourse has produced a great deal of works in several languages pointing to different aims: from studies where the identification of cues about the planning of linguistic message is treated to studies in which duration models for text-to- speech systems are proposed. This work is a first step towards the description of Catalan vowel duration. Considering the Catalan vowel system, two subsystems can be distinguished according to stress: stressed vowels: /i/, /e/, /E/, /a/, /O/, /o/, /u/, and unstressed vowels /i/, /u/, /@/. The purpose of the present study is to provide data for Catalan vowels in order to achieve a data-oriented description and at the same time a predictive model suitable to be implemented in a TTS system.