We have developed a silicon-based neural microelectrode system for long-term neural recording and stimulation. Our aim is to design robust silicon-based microelectrode arrays that are suitable for implantation into various targets in the brain and spinal cord. The microelectrode sites were electroplated with iridium oxide, thereby reducing the AC impedance and increasing charge storage capacity, compared to gold electrodes. To date, the implanted probe system has been able to record resolvable single-unit action potentials for five months in the ventral cochlear nucleus of the cats' brainstem.