SUMMARY— The rates of several deteriorative reactions, including lipid oxidation, astacene pigment loss, carbon dioxide production, and production of non-enzymatic browning pigments, were studied in freeze-dried salmon at 37°C and at several relative humidities. Results previously obtained in cellulosic model systems containing methyl linoleate were confirmed by data on oxygen absorption as a function of moisture content. Both the rate of the initial peroxide mono-molecular decomposition and the peroxide value decreased as the water content was increased. Astacene pigment loss was reduced significantly by the higher moisture contents; non-enzymatic browning was increased. The significance of the reactivity of water at low moisture contents was demonstrated by its effect on the various reactions.