Heat and mass transfer in direct contact membrane distillation (MD) has been analyzed by using a specifically designed cell. In particular, the cell has sixteen sensors located at specific locations within its body to measure the bulk and membrane surface temperatures on both feed and permeate sides. The effect of various hydrodynamic and thermal conditions on heat and mass transport in direct contact membrane distillation has been investigated experimentally. The effect of solution concentration and thermal polarization on membrane distillation performance has been explored quantitatively. A good agreement between the experimental and theoretical results has been observed.