The study of Portuguese fricatives is a complex problem, which has not been explored fully. As partof a larger study of the acoustic properties of Portuguese fricatives, corpora of Portuguese words containing /f, v, s, z, A, O/, nonsense words with Por-tuguese phonology, and sustained Portuguese frica-tives have been recorded and analysed. Results showthat more than half of the voiced fricatives devoice.Averaged power spectra were computed for all fricatives; differences between fricatives, in particular related to syllable stress, are described.