Gestures and vocal elements interact from the early stages of language development, but the role of this interaction in the language learning process is not yet completely understood. The aim of this study is to explore gestural accompaniment's influence on the acoustic properties of vocalizations in the transition to first words. Eleven Spanish children aged 0;9 to 1;3 were observed longitudinally in a semi-structured play situation with an adult. Vocalizations were analyzed using several acoustic parameters based on those described by Oller et al. (2010). Results indicate that declarative vocalizations have fewer protosyllables than imperative ones, but only when they are produced with a gesture. Protosyllables duration and f(0) are more similar to those of mature speech when produced with pointing and declarative function than when produced with reaching gestures and imperative purposes. The proportion of canonical syllables produced increases with age, but only when combined with a gesture.