For last five years polymers have revolutionised all spheres of human endeavour and, therefore, have been the focus of intense investigation by academic and industrial researchers. One of the most important problems in polymer applications is a comprehension of water transport phenomena attending to production, exploitation, and storage of polymer materials or articles. Conceptually this collection is partitioned into three, thematically bonded sections including academic aspects, experimental procedures, and practical application aspects including such intriguing subjects as exposure of polymer composites to earth orbit space environments. Advancement in the understanding of specific behaviour of water in polymers with different hydrophilicity and morphology has to open the way to design the novel constructional and biomedical materials as well as ecologically friendly packaging films and selective membranes.