The paper presents our results of studies on the synthesis of conducting polymer microislands using self-assembled thiol monolayers containing pinhole defects. It was found that in consequence of. electrochemical oxidation of the corresponding monomers (aniline o-methoxyaniline 2,5-dimethoxyaniline) on gold coated with long-chain alkanethiols the polymer is being formed in a localized manner starting the growth from thiol film defects. Therefore, the conducting polymer microislands can be created on the thiol-coated substrate in such a way. The sizes and distribution of the synthesized microislands were estimated on the basis of microscopic and electrochemical measurements. It was found that the polymer microstructures can be switched between a conducting and nonconducting state by application of the appropriate potential to the metal electrode. When oxidized (conducting), the microstructures behave like an array of microelectrodes, but when reduced (nonconducting form), the whole thiol/polymer layer reveals blocking properties.