Membrane distillation (MD) is a separation process based on the vapor transport across the hydrophobic microporous membrane driven by the vapor pressure gradient across the membrane. This process can be used for various applications such as seawater desalination, wastewater treatment, separation of volatile compounds, concentration of non-volatile compounds and processing of dairy fluids. Comparing with other separation processes, the MD process possesses unique characteristics such as 100% (theoretical) rejection, mild operation conditions, insensitive to feed concentration and stable performance at high contaminant concentrations. Due to high oil prices in recent years, extensive research has been devoted to MD in the areas of membrane materials, module configurations, process applications and hybrid systems. This review aims to summarize the recent advances in MD and provide perspectives for its future R&D. (C) 2014 Elsevier B.V. All rights reserved.