The paper focuses on the particular Hittite religious expression represented by the celebration of festivals connected to the natural phenomenon of thunder. Interpreted as a manifestation of the Storm- God, thunder was perceived in Hittite religious thought as potentially dangerous for the wellbeing of the king. It demanded therefore the execution of particular rites. The texts describing these ceremonies are collected under the numbers 630 and 631 of the Catalogue des Textes Hittites. They show several interesting features, concerning both the content and the internal structure of the compositions, which reflect in my opinion the attempt to adapt a standard ritual practice to an unpredictable event such as thunder.