The end coupling of living PSLi chains in hydrocarbon media by the addition of monoalkyl bromides has been examined. A very selective PS-PS coupling reaction was obtained with neo-pentylbromide (94%) at a ratio of PSLi/alkylbromide equal to 1 while the secondary and tertiary bromine derivatives yield only very limited coupling The coupling mechanism is likely to involve a lithium-bromine interchange at the PS chain end, generating polystyryl-bromide which then reacts selectively with the remaining polystyryllithium chains.