Coconut water is an increasingly popular raw material, mainly due to its hydrating and health-promoting properties. The aim of the work was to develop exemplary model fruit mousses with coconut water and to evaluate the effect of thermal fixation processes on the stability of polyphenols and antiradical activity, which were pasteurized and stored for 6 months in real conditions. The nutritional value of the mousses, i.e. the content of vitamins and minerals, was determined, and the influence of storage on the content of polyphenols and antioxidant properties measured with the DPPH radical and ABTS•+ radical cation methods was assessed. It has been shown that coconut water can be an ingredient in mousses, which allows for the creation of new dessert products. It was found that the developed products contained compounds of antioxidant nature. The highest content of phenolic compounds was found in the sample with the addition of protein 178.43b±11.39 µg gallic acid/mL. The content of polyphenols in the tested samples was stable during storage. In the test with the use of ABTS•+ radicals, the highest activity was shown by mousse with the addition of caffeine tested one day after preparation (4.43a±0.24 TE/g dw), while in the test with the use of DPPH radicals, the sample tested one day after preparation with the addition of almond protein had the highest activity anti-radical (6.87a±0.37 TE/g dw). The highest total acidity was recorded in the case of mousses with the addition of almond protein (MPr - 0.84a±0.03 g / 100 g).