Stress detection in a second/foreign language (L2) is a complex task which depends of different linguistic and cognitive factors. The objective was to investigate to what extent the activation of specific brain regions involved in L2 stress perception was related to the listeners' ability to detect L2 stress, and to their stress learning capacity. French-speaking participants with no knowledge of Spanish took part in an fMRI study in Spanish, as well as in a pre/post-training experiment, also in Spanish. Results showed that native listeners of French improved their stress perception in a L2 after training, even though the training effect was rather subtle and interindividually variable. The results also revealed that there was a link between neural activation in left inferior frontal gyrus and the participants' performance in L2 stress identification before training. No correlation was found with the amount of learning after training. These data highlight the fact the interindividual differences observed in L2 stress processing might be (at least partially) related to neural interindividual differences.