There　is　a　great　potential　of　gelatin　to　be　applied　in　food　packaging,　tissue　engineering,　and　drug　delivery　due　to　its　biocompatibility,　edibility　and　biodegradability.　However,　the　main　issue　with　use　of　native　gelatin　based　materials　in　practical　application　is　their　water　solubility　and　poor　thermostability　as　they　are　rapidly　dissolved　in　warm　solution.　In　order　to　improve　their　water-resistant　ability　and　thermo-mechanical　performance,　the　gelatin　bars　or　membranes　were　cross　linked　by　chlorine　dioxide　(ClO2)　vapor　at　room　temperature.　An　exposure　of　the　gelatin　materials　in　ClO2　vapor　for　12　h　generated　a　cross-linking　extent　sufficient　to　preserve　their　morphology　in　37　degrees　C　warm　water　for　above　5　days.　The　cross-linking　also　led　to　improved　thermostability　and　enhancement　in　mechanical　properties.　Energy　dispersion　X-ray　analysis　indicated　that　no　halogen　substitution　reaction　happened　in　the　cross　linking　reaction,　and　the　residual　Cl　could　be　removed　thoroughly　by　pretreatment.　Cytotoxicity　was　evaluated　based　on　a　cell　proliferation　study.　It　was　found　cell　expansion　took　place　and　linearly　increased　during　the　course　of　whole　period　of　the　cell　culture.　Thus　the　cross-linked　material　showed　no　toxicity　to　the　cells.　(C)　2014　Elsevier　Ltd.　All　rights　reserved.