[en] The Szilard-Chalmers recoil of the cations La³⁺, Ba²⁺, Co²⁺, Zn²⁺, Cu²⁺, Cs⁺, Rb⁺, K⁺, Na⁺ and Ag⁺ located in the supercage sites of zeolites X and Y has been studied. After irradiation with thermal neutrons approximately 90% of the recoiling cations are found in the supercage sites with La³⁺, Ag⁺ and Na⁺ being the only exceptions. The figure of 90% has been shown to be independent of the character of the cation located in the sodalite cages and hexagonal prisms of these faujasite type zeolites and also independent of the charge density of the framework. (author)