The invention relates to an appliance for the continuous photocatalytic purification of the air in a room, said appliance preferably being in the form of a wall (1) and comprising an external steel structure, an opening (11) for the admission of the air to be processed, an internal metallic framework (4) to which a plurality of UVA lamps (3) are fixed, a photocatalytic filter (2), and an opening (12) for discharging the purified air. The inventive appliance is characterised in that the photocatalytic filter comprises at least one metal grating (2) covered by a film containing titanium dioxide (TiO.sub.2), mainly in an anatase phase, in order to maximise the surface of the photocatalyst illuminated by the UVA light.