In this paper, we investigate the CO2 microbubble removal on carbon nanotube (CNT)-supported Pt catalysts in direct methanol fuel cells (DMFCs). The experiments involve the incorporation of near-catalyst-layer bubble visualization and simultaneous electrochemical measurements in a DMFC anodic half cell system, in which CH3OH electro-oxidation generate carbon dioxide (CO2) microbubbles. We observe rapid removal of smaller CO2 bubble sizes and less bubble accumulation on a Pt-coated CNT/CC (Pt/CNT/CC, CC means carbon cloth) electrode. The improved half cell performances of the high CO2 microbubble removal efficiency on the CNT-modified electrode (Pt/CNT/CC) were 34% and 32% higher than on Pt/CC and Pt/CP electrodes, respectively.