Catalyst particles are prepared by coating a core particle, which is usually catalytically inert with respect to the intended chemical reaction, in a fluidized bed coating apparatus. The coating technique involves repeatedly applying and drying small quantities of an atomized slurry containing the coating material in the form of a colloidal dispersion or in the form of very fine, non-colloidal particles preferably mixed with colloidal particles. In this way, incremental layers are formed to produce a final thin shell which has a highly uniform thickness, which is formed on the surface of the core and which does not penetrate porous cores. Various methods are disclosed for converting the coated particles to the desired catalyst form.