Experiments were conducted to evaluate the rate of water vaporisation and the consequent permeability reduction caused by the flow of dry gas through porous media. Two sets of porous media were studied: unconsolidated Ottawa sandpacks and consolidated Berea cores, as well as various salinity brines ranging from 0 to 150 g/litre of NaCl. The experiments were conducted at an initial water saturation of about 14% for sandpacks and 24.6% for Berea cores. Tests indicate that the rate of water vaporisation increases with gas flow rate and decreases with salinity. The vaporisation of water from the porous media can result in halite drop-out. This might cause a reduction in the permeability of the porous media. The experiments showed that the reduction in permeability for sandpacks ranged from 0% for the lowest salinity to around 21% for the highest salinity used. In consolidated Berea cores this reduction ranged from 9% to 53% for the lowest and highest salinity respectively.