Poly(Ionic Liquid)s (PILs) are a class of ionic liquids that feature polymerizable groups in either the cation, the anion or both. PILs can be used in various applications, including solid ion conductors or for CO2 absorption. Several PILs show the presence of a lower critical solution temperature (LCST), making them suitable precursors for the synthesis of stimuli-responsive materials that have the ability to change their conformation in response to variations in their external environment. The aim of this study was to synthesise crosslinked PIL hydrogels, namely poly(tributylhexyl phosphonium sulfopropyl acrylate) (PSPA) using different crosslinkers, and to characterise their swelling/contracting behaviour under varying temperature and salt solution compositions.