State-of-the-art barrier materials play a significant role in various technical applications, especially as the aspect of recycling becomes more and more important. Due to properties such as high water solubility and good food compatibility, polyvinyl alcohol and its copolymers exhibit certain advantages in comparison to other polymeric and metallic materials that are used as barrier layer materials. The present work therefore concerns the use of polyvinyl alcohol and poly(vinyl alcohol-co-vinyl amine) as barrier layer materials in polymeric composites for several technical applications (e.g., packaging, building materials, pipe systems and medical engineering), which necessitate specific material properties. Hence, the permeation of water, water vapour, hydrocarbons and non-volatile organic compounds was measured with different methods to determine the permeability of the barrier layer materials. Firstly, studies concerning the influence of chemical structural properties such as degree of hydrolysis, degree of crystallization or molecular weight on the barrier properties were performed. Based on these results the possibility of adjusting the permeability by crosslinking or the addition of fillers was investigated. For the improvement of the flexibility of the barrier layer material, which is important for medical applications, different blends were developed followed by an evaluation of their barrier properties. Finally, the properties of the barrier layer materials in polymer composites were tested. The results show that polyvinyl alcohol and poly(vinyl alcohol-co-vinyl amine) can be used to reduce the permeation of organic and inorganic gases. Furthermore, the permeability can be adjusted by various modifications.