The new evidences of morphology dependent electrocatalytic activity for CO oxidation have been presented. Different morphological micro-sized Bi2O3 supports, with Bi2O3 flowers-like and tubes-like characteristics, have been synthesized. The Pt was deposited on the supports by photo-deposition method. It has been found that the micro-sized flowers-like supported Pt/Bi2O3 catalyst exhibits higher peak current densities, more negative onset potential, peak potential, and higher electrocatalytic activity for CO oxidation, compared with Pt/Bi2O3 microtubes. XRD and HR-TEM results indicate that there is a stronger interaction between Pt species and Bi2O3 flowers-like support.