The invention relates to a process for producing highly conducting and highly transparent thin films based on poly(3,4-ethylene dioxythiophene):polystyrene sulphonate (PEDOT:PSS),comprising the steps of coating thin films of PEDOT:PSS dispersion on a substrate and treatingthe films obtained in step (b) by a solution of an organic acid in a suitable solvent. It further alsorelates to application of these highly conducting and highly transparent thin films in transparent conductors in Liquid Crystal Display, Flexible Displays, Thin film transistors, Organic Displays,Transparent electrodes, Electrochromic displays etc'.