Frost formation inside food hermetic packages preserved in domestic freezer was studied. The influence of the following factors on frost formation was studied experimentally: product characteristics and package insulation. The frost deposits particularly on the product located in the central zone of the box and on the bottom horizontal surface of the box. An interpretation of the results shows that frost develops in the zone where the temperature is low in the box and/or where the temperature variation is low. This is the case at the bottom of the box (thermal stratification) and at the centre (thermal inertia).