Process for through-hole plating of printed circuit boards and multilayers by applying a conductive layer of a polythiophene onto the walls of the through-holes and electrodeposition of copper onto the walls of the through-holes, characterized in that a microemulsion of a monomeric thiophene of the formula (I) is used to form the conductive polythiophene layer, ##STR1## in which X denotes oxygen or a single bond,R.sub.1 and R.sub.2 mutually independently denote hydrogen or a C.sub.1 -C.sub.4 alkyl group or together form an optionally substituted C.sub.1 -C.sub.4 alkylene residue or a 1,2-cyclohexylene residue,and in that the conductive layer of polythiophene is produced on the walls of the through-holes by subsequent or simultaneous treatment with acid and, finally, a metal is electro-deposited on this conductive base.