The organizers of this Fifth Symposium maintained their initial objectives, namely to gather experts from both industries and universities to discuss the scientific problems involved in the preparation of heterogeneous catalysts, and to encourage as much as possible the presentation of research work on catalysts of real industrial significance. Another highlight of these symposia was to reserve a substantial part of the program to new developments in catalyst preparation, new preparation methods and new catalytic systems. The fact that chemical reactions which were hardly conceivable some years ago have become possible today through the development of appropriate catalytic systems proves that catalysis is in constant progress. The papers in this volume deal with studies of unit operations in catalyst preparation, catalyst preparation via the sol-gel route, preparation of catalysts from layered structures and pillaring of clays, preparation and modification of zeolite-based catalysts, carbon supported catalysts, preparation of oxidation catalysts and novel and unusual preparation methods.