Abstract: Dynamic characteristics are very important for transportable power sources with direct methanol fuel cells. The dynamic voltage responses to variable current of a single direct methanol fuel cell were studied.With the aid of computer-controlled electronic load, cell potential dynamic responses to current loading cycle,magnitude of loading current, constant loading/rest time and slope of increasing current were investigated. Experimental results indicated that the fuel cell responded rapidly to dynamic change of current cycle. Open circuit voltage of the fuel cell under dynamic operating condition was higher than that under steady state operating condition.The slope of increasing current significantly affected the cell dynamic response.The interaction between electrochemical reactions and transient heat/mass transfer inside the fuel cell made key contribution to dynamic response of the fuel cell.