Sulphonic acid derivatives of polyethers, of interest as proton conducting materials, were investigated using Raman spectroscopy, focusing on influence of hydration on ion configuration and polymer conformation. Upon increasing hydration we observe a polarised mode building up at approximately 1040 cm(-1), assigned to the symmetric stretching vibration of a completely hydrated SO3- group. The data suggest that the proton-sulphonic groups do not dissociate until the materials are considerably hydrated thus explaining the low proton conductivities found for these materials below a relative humidity of 75%.