Procedure for marking, encryption, labelling and optical coding (PCT/ES2010/070054) It permits marking or recording motifs on surfaces whereon there has been deposited previously a fluorescent polymer layer through a procedure of plasma polymerisation of molecules of a colourant. The procedure combines the special characteristics of the polymer layers making them suitable for being capable of recording diverse motifs thereon, and the possibility of recording by laser or other techniques. Among such characteristics should be mentioned the possibility of a notable visual effect, including for thicknesses of 100 nm, the use of layers non-observable when illuminated with visible light, the high optical quality (transparency) thereof, or the facility wherewith they may be processed by subsequent treatments, including diverse laser treatments.