The　infiltration　of　ions　into　hydrogel　matrix　could　significantly　affect　the　microstructure　and　macroscopic　mechanics　of　the　gels.　Here,　the　Hofmeister　effect　of　various　salts　on　the　whey　protein　isolate　hydrogels　with　fine-stranded　and　particulate　microstructures　is　investigated　by　soaking　the　preformed　hydrogels　in　the　sodium　salts　of　different　anions.　The　infiltration　of　kosmotropic　anions　yield　stiffer　hydrogels,　whereas　the　chaotropic　anions　soften　the　hydrogels.　The　hydrogels　with　fine-stranded　microstructures　are　more　sensitive　to　the　salts　comparing　to　the　particulate　ones　due　to　the　microscopic　phase　transitions　and　enhanced　hydrophobic　interactions　between　polymer　chains　occurred　in　fine-stranded　hydrogels.　Besides,　despite　the　significant　difference　in　water　binding　ability　of　different　salts,　the　water　holding　capacity　of　the　salt-treated　hydrogels　was　mainly　determined　by　the　gel　stiffness　instead　of　the　salt　types.　Similar　mechanical　responses　of　BSA　and　egg　white　protein　hydrogels　to　the　Hofmeister　series　was　also　demonstrated,　suggesting　that　the　results　shown　here　could　potentially　be　generalized　for　other　globular　protein　hydrogels.　©　2020　Elsevier　B.V.