A random assembly of microelectrodes (RAMs) was fabricated by electrochemical reduction of 5-bromo-1,10-phenathroline in N,N-dimethylformamide (DMF), generating the 1,10-phenanthroline radical, which was covalently grafted on gold electrodes. After several potential cycles, the gold surface was partially blocked with an insulating film of 1,10-phenanthroline and the resulting modified electrode exhibited the characteristics of a RAMs for the electrochemical reduction of the reversible probe 1,4-benzoquinone in DMF. Scanning electron microscopy and atomic force microscopy were used to examine the morphology of the electrodeposited film and to characterize the existence of micro-regions of gold not coated by the 1,10-phenanthroline film.