Technical Abstract: Water vapor permeability of cold and warm-water fish skin gelatins was evaluated and compared with different types of mammalian gelatins. Mammalian, warm and cold-water gelatins were obtained from commercial sources. Alaskan pollock and salmon gelatins were extracted from frozen skins. Water vapor permeability of 100% gelatin films was determined using the ASTM E96-80 method, modified to calculate the % relative humidity at the film underside. Molecular weight distribution, amino acid composition, gel strength, viscoelastic properties, pH and clarity were also determined for each gelatin. Water vapor permeability of cold-water fish gelatin films was 0.93 g.mm/m2.h.kPa and significantly lower than warm-water fish and mammalian gelatin films (1.31 and 1.88 g.mm/m2.h.kPa, respectively) at 25°C, 0/80 %RH through 0.05 mm thickness films. This is related to increased hydrophobicity due to reduced amounts of proline and hydroxyproline in fish gelatins. As expected, gel strength and gel setting temperatures were lower for cold-water fish gelatin than either warm-water fish gelatins or mammalian gelatins. This study demonstrated significant differences in physical, chemical and rheological properties between mammalian and fish gelatins. Lower water vapor permeability of fish gelatin films can be useful particularly for applications related to reduce water loss from encapsulated drugs, and refrigerated or frozen food systems.