A process of lyophilization for the preparation of a piroxicam:ß-cyclodextrin inclusion compound in a 1:2.5 molar ratio comprising the steps of dissolving piroxicam and ß-cyclodextrin in the molar ratio of 1 to 2.5 and ammonium hydroxide in water brought to a temperature comprised between 70 and 75°C pouring the hot solution of step a) on the temperature-controlled shelves of a freeze-dryer wherein said shelves of said freeze-dryer are pre-cooled to a temperature of at least -30 °C bringing the hot solution to the temperature of -10°C of complete freezing and drying the frozen solution under vacuum characterized in that the temperature of -10°C of complete freezing of the hot solution of step a) is achieved at a cooling rate equal to or higher than 10C/min.
