Palatalisation of /l/ in obstruent + lateral onset clusters in the absence of a following palatal sound has received a considerable amount of attention from historical linguistics.The phonetics of its development, however, remains less wellinvestigated.This paper aims at studying the acoustic cues that could have led plosive + lateral onset clusters to develop palatalisation.It is found that onset clusters with velar plosives favour palatalisation more than labial + lateral clusters, and that a high degree of darkness diminishes the likelihood of palatalisation to take place.