Purpose Research has shown that observing hand gestures mimicking pitch movements or rhythmic patterns can improve the learning of second language (L2) suprasegmental features. However, less is known about the effects of hand gestures on the learning of novel phonemic contrasts. This study examines (a) whether hand gestures mimicking phonetic features can boost L2 segment learning by naive learners and (b) whether a mismatch between the hand gesture form and the target phonetic feature influences the learning effect. Method Fifty Catalan native speakers undertook a short multimodal training session on two types of Mandarin Chinese consonants (plosives and affricates) in either of two conditions: Gesture and No Gesture. In the Gesture condition, a fist-to-open-hand gesture was used to mimic air burst, while the No Gesture condition included no such use of gestures. Crucially, while the hand gesture appropriately mimicked the air burst produced in plosives, this was not the case for affricates. Before and after training, participants were tested on two tasks, namely, the identification task and the imitation task. Participants' speech output was rated by five Chinese native speakers. Results The perception results showed that training with or without gestures yielded similar degrees of improvement for the identification of aspiration contrasts. By contrast, the production results showed that, while training without gestures did not help improve L2 pronunciation, training with gestures improved pronunciation, but only when the given gestures appropriately mimicked the phonetic properties they represented. Conclusions Results revealed that the efficacy of observing hand gestures on the learning of nonnative phonemes depends on the appropriateness of the form of those gestures relative to the target phonetic features. That is, hand gestures seem to be more useful when they appropriately mimic phonetic features. Supplemental Material https://doi.org/10.23641/asha.13105442.