This work focuses on vacuum membrane distillation (VMD) for seawater desalination. The aim of the work was to compare two hollow fibre module configurations (inside/out and outside/in). Experiments were carried out with pure water and with 15 g/L up to 300 g/L NaCl solutions and for two different material and structure of fibres. Pure water permeability and global heat transfer coefficient were compared for the two configurations. The influence of hydrodynamics on global heat and mass transfer coefficients is discussed.