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Our previous study demonstrated that cobalt content strongly affected the electro-activity of aluminum pillared clay-supported cobalt (CoAP) toward glucose oxidation. It was found that the electro-activity of CoAP increased with the increase of cobalt loading. However, at the 10 wt.% of cobalt content, the electro-activity significantly decreased. In the present study, the focus is on the investigation of the nature of the surface sites that might cause the difference in the electro-activity of CoAP. For this purpose, CoAP with 3 wt.% and 10 wt.% cobalt contents (x%CoAP, x=3 and 10) were characterized using FE-SEM and HR-TEM with EDX techniques, and XPS. The microscopic techniques coupled with EDX have shown that cobalt oxide nanoparticles were evenly distributed in both samples. However, the higher cobalt loading resulted in cobalt oxide agglomeration that led to larger particle sizes. The results of XPS confirmed the presence of Co (II) in the 3%CoAP. On the other hand, the presence of Co3O4 which contains both Co (II) and Co (III) was confirmed in 10%CoAP. It is clear from this study that the electro-activity of CoAP strongly depends on the oxidation state of cobalt. However, the effect of agglomeration and cobalt oxide particle sizes cannot be ruled out.