Cyclic voltammetry (CV) at slow scan rate is usually performed to characterize the electrochemical behavior of microelectrodes. Early in vitro study on over 200 activated iridium oxide film (AIROF) microelectrodes showed variability of their electrochemical behavior. In this paper, we reported CV measurements under 3 different scan rates for 96 AIROF microelectrodes. We traced their behavior during 7 stages of fabrication and processing starting from prior to activation, and ending with post-implantation in the experimental animal. The results show that even at the early stage of electrode activation, variations between near identical electrodes existed.