A relationship between the electro-optic switching time and dielectric parameters of a S*cferroelectric liquid crystal (FLC) is obtained. This relationship is derived in terms of spontaneous polarizationPs, relaxation time τGand dielectric strength ΔεGof the Goldstone mode. It shows clearly that the switching phenomenon in FLCs is governed by the dielectric behaviour of the Goldstone mode. Based on the Landau model, the switching time has also been related to the material parameters of the FLC.