Background <p>The Utah electrode array (UEA) is a promising microelectrode technology with potential applications to assist patients with sensory loss, spinal cord injuries, and limb loss serving as neural prosthetics and brain-computer interfaces. Performance lifetime of microelectrodes, particularly when used for stimulation, remains one of the challenges for their clinical translation.</p> Methods <p>This study characterizes the stimulation stability of an optimized iridium oxide (IrOx) <i>research</i> metallization for the UEA in comparison to the Blackrock standard practice metallization. The stimulation stability (Stim-Stab) protocol used electrochemical characterization and either 10⁶ or 4 × 10⁶ pulses at 2,100 <i>µ</i>A (420 nC/ph) with longitudinal voltage transient measurements and physical characterization to quantify electrode lifetime.</p> Results <p>Approximately 50% of electrodes using the Blackrock standard practice process electrical failed during 10⁶ pulses, whereas no electrical failures were observed from 4 × 10⁶ pulses for the <i>research</i> metallization. Backscattered scanning electron microscopy (BSEM) determined that all electrodes with electrical failures during Stim-Stab testing had complete loss of metallization. Of electrodes with good electrical outcomes from Stim-Stab testing 80% and 50% of those had notable metallization damage for <i>BRM</i> and <i>research</i> metallization, respectively.</p> Conclusions <p>These results suggest that the <i>research</i> metallization makes important steps for improving electrode metallization lifetime of Utah arrays. Additionally, the Stim-Stab method provides valuable feedback for engineering improved electrode metallization.</p>