The objective of the present work was to determine the amount of water transported across the membrane from the cathode to the anode using dry gas operation of PEMFC of various electrode areas starting from 30, 114 and 370 cm2, and to compare the product water drag from the cathode to the anode by diffusion at various power levels. As a preview to a stack running on dry gas, a two-cell assembly of 370 cm2 area was also operated. The aim of the presentwork was to identify the main factors that determine the water transport while operating with dry gas, especially by back diffusion.