An experiment is presented here concerning perception of release bursts in a corpus of natural tokens of French /p,t,k/ in CV context. The focus of the study was the perceptual role of spectral characteristics of the release burst; therefore tokens have the same duration of nearly 25 ms so that neither VOT nor formant transitions may influence listeners. Two training sessions appeared to be necessary to reach the utmost of listeners' ability to identify stops. Results show that the recognition rate are approximately the same for /p/ (89%), /t/ (87%) and /k/ (86%). More precisely, identification of /k/ in the context of a front vowel is not so high (75%) and is often confused with /t/; /k/ in the context of a back vowel is very well identified (98%). /t/in the context of /y/ or / / is confused (22%) with /k/. These very high identification rates militate in favour of acoustical invariants, even if, in some cases (for example in the context of a back vowel), the knowledge of the subsequent vowel may help the stop identification. Therefore, in order to provide further indication concerning the design of an analytical stop recognition system we plan to examine the role of prior knowledge of the subsequent vowel type.