We demonstrated fixing of conducting polymers onto hydrogen-terminated Si(100) surfaces via a pulse valve. The pulse-injected molecules were multiwalled carbon-nanotube, π-conjugated poly(3-hexlthiophene-2,5-diyl), poly(N-tert-butoxycarbonyl diphenylamine-4,4'-diyl), and poly((3-hexylthiophene-2,5-diyl)-co-(diphenyldisulfide-4,4'-diyl)). Each sample was dispersed or dissolved in a certain solvent before pulse injection. In all cases, the isolated molecules were observed by scanning tunneling microscopy. The results indicate that the pulse injection method can be used for fixing and isolating various conducting polymers. [DOI: 10.1380/ejssnt.2004.28]