The preparation of heterogeneous catalysts has by now lost all empirical aspects. The approach is scientific and involves a wide number of specific competencies of solid state chemistry, analytical chemistry, physical chemistry, kinetics, theology, etc. The fundamental aspects in the preparation of heterogeneous catalysts starting from catalyst design up to the catalyst in its final form are briefly reviewed, with focus on the key factors in each preparation step and the main differences between laboratory and industrial scale preparations. The main properties of monolithic catalysts and their preparation methods are also reported, considering their relevance for environmental applications.