A new module design for membrane distillation, namely material gap membrane distillation (MGMD), for seawater desalination has been proposed and successfully tested. It has been observed that employing appropriate materials between the membrane and the condensation plate in an air gap membrane distillation (AGMD) module enhanced the water vapor flux significantly. An increase in the watervapor flux of about 200-800% was observed by filling the gap with sand and DI water at various feed water temperatures. However, insulating materials such as polypropylene and polyurethane have no effect on the water vapor flux. The influence of material thickness and characteristics has also been investigated in this study. An increase in the water gap width from 9 mm to 13 mm increases the water vapor flux. An investigation on an AGMD and MGMD performance comparison, carried out using two different commercial membranes provided by different manufacturers, is also reported in this paper. (C) 2013 Elsevier B.V. All rights reserved.