To　describe　precisely　the　chemo-mechanical　coupling　behavior　of　hydrogels,　a　general　form　of　free　energy　density　function　is　presented　by　considering　chain　entanglements　and　functionality　of　junctions.　We　use　the　chemical　potential　of　the　solvent　and　the　deformation　gradient　of　the　network　as　the　independent　variables　of　the　developed　free　energy　function,　and　implement　this　material　model　in　the　finite　element　package,　ABAQUS,　to　analyze　several　examples　of　chemo-mechanical　equilibrium　deformation　behaviors　of　hydrogels.　The　influence　of　chain　entanglements　and　junction　functionality　on　the　chemo-mechanical　behavior　of　hydrogels　is　addressed　based　on　our　simulation.　With　the　coded　subroutine　UHYPER,　this　work　may　provide　a　numerical　tool　to　study　complex　phenomena　in　hydrogels.　(C)　2013　Elsevier　Ltd.　All　rights　reserved.