The present invention relates to an improved photolithography process particularly suitable for high-resolution optical lithography techniques using the g, h and i lines of the spectrum of mercury and short-wavelength UV, comprising, prior to deposition of the photosensitive resin on the layer of material to be lithographically patterned, the formation of an antireflective porous layer within the said layer to be lithographically patterned and on the surface of the latter.