The invention relates to a photocatalyst comprising a beta-SiC cellular foam and a photocatalytically active phase, deposited directly on said cellular foam or on an intermediate phase deposited on said cellular foam. The average size of the cells is between 2500 mum and 5000 mum. The foam can comprise nanotubes or nanofibers (particularly of carbon, SiC, and TiO2) that consist of, or carry as an intermediate phase, a photocatalytically active phase.