The present contribution investigates the pronunciation of German plosives by 15-year- old students from the Italian part of Switzerland. In particular, VOT and %Voice (the percentage of duration by which the signal of ‘voiced plosives’ is periodic) are analysed. In a classroom experiment, 10 students received detailed instructions about the phonetic differences between German and Italian plosives and were recorded twice in a reading task (prior and after the instruction). A control group of 10 students without explicit pronunciation training was recorded twice as well. No statistically significant effects of the explicit pronunciation training were found, at least for the group as a whole; only four students showed clearly higher VOT values of the voiceless German plosives in the second recording. Implications for pronunciation teaching and further research are discussed.