The genesis and subsequent sintering in a hydrogen atmosphere of realistic Cu/amorphous silica planar model catalysts have been investigated by atomic force microscopy. Samples were prepared by standard wet chemical methods followed by calcination and reduction, mimicking as closely as possible the procedures used in the preparation of practical, dispersed Cu catalysts. Changes in size distribution and mean particle size are observed as the sequence of transformations, Cu nitrate --> cupric oxide --> Cu metal, proceeds and an interpretation is offered. Pronounced sintering in hydrogen is the result of migration, agglomeration and coalescence of entire Cu particles, as opposed to Ostwald ripening. A mechanism for this process is proposed on the basis of absorption/desorption of hydrogen at steady state.