In present work, a 600 h durability test and in situ measurements of water transport were carried out on a single direct methanol fuel cell (DMFC) at atmospheric pressure and 80 degrees C. Effect of water transport on the single cell performance was investigated in detail, which indicated that the accumulated water in the hydrophobic micropores of the cathode gas diffusion layer (GDL) aggravated the cathode flooding, and consequently led to a temporary and reversible degradation of the cell performance. Further investigation revealed that cathode flooding could be alleviated by blowing the cathode with dry air for 150 h at open circuit condition and the partially recovered cell performance within the durability could be obtained in consequence. Water analysis combined with the scanning electron microscopy (SEM), contact angle measurement and energy dispersive X-ray (EDX) was used to explore the characteristics of cathode GDL before and after the durability test. Results showed that the variation of the microstructure and hydrophobic properties for both sides of the cathode GDL is probably one of the inherent reasons for the irreversible degradation of the cell performance besides the electro-catalysts deterioration. (c) 2008 Elsevier B.V. All rights reserved.