The invention relates to a self-cleaning system (10) and window glass. The self-cleaning system comprises a translucent substrate (20), a light-emitting device (30) and a photo-catalytic layer (40) applied to a surface (22) of the translucent substrate for generating a self-cleaning surface. The photo-catalytic layer produces the self-cleaning effect when illuminated with light of a predefined wavelength range. The translucent substrate is translucent for at least a sub-range of the predefined wavelength range. The light-emitting device is arranged for illuminating the photo-catalytic layer via the translucent substrate, an emission spectrum emitted by the light-emitting device comprising light within the sub-range. The effect of the illumination system according to the invention is that the illumination of the photo-catalytic layer via the translucent substrate enables the light-emitting device to be arranged relatively near to the photo-catalytic layer such that only a relatively low light flux is required from the light-emitting device to activate the self-cleaning process.