Metal-air batteries are considered as one of the best alternatives to current Li-ion batteries with their high energy densities (1000-13000 Wh/kg) also, they are lightweight, cheap and safe. However, secondary alkaline metal-air batteries suffer from catalyst corrosion, anode passivation and corrosion, electrolyte loss and pore clogging leading to performance loss and reduced cycle life. This thesis aims to evaluate the feasibility of highly cross-linked, hydrophobic, and oxygen selective thin homopolymers and copolymers films as potential candidates for Gas Diffusion Layer (GDL) materials in Gas Diffusion Electrodes (GDEs) for alkaline metal-air batteries. Homopolymers of 2,4,6,8- tetramethyl-2,4,6,8-tetravinylcyclotetrasiloxane (V4D4), 2-(perfluorohexyl)ethyl acrylate (PFHEA) and 2-(perfluoroalkyl)ethylmethacrylate (PFEMA) and their copolymers were synthesized via initiated chemical vapor deposition (iCVD). iCVD deposited fluoropolymer thin films exhibited low water transmission rates and excellent oxygen diffusion with a high oxygen/water selectivity up to 13.6. GDEs with iCVD GDLs exhibited higher oxygen reduction current density (228.2 mA cm-2) when compared to commercial counterparts (132.7 mA cm-2). In addition, the chemical stability, durability and corrosion protection aspects of these films were investigated by substrate adhesion and immersion tests in organic solvents and NaCl solution. The results of corrosion test together with chemical stability and durability evaluation indicate that iCVD deposited copolymers exhibit excellent adhesion, good solvent resistance and offer an effective physical and chemical protection without the need for surface pretreatment. iCVD copolymer films provide better anti corrosion barrier with lower corrosion efficiency (85-99 %) for metal surface compared to homopolymer counterparts. By combining siloxane and fluorinated matrix, the copolymer films provide enhanced oxygen transport and reduce moisture entrance significantly as a GDLs and also improve physical, chemical, corrosion protection. Keywords: Metal-Air Batteries, Gas Diffusion Electrode, Gas Diffusion Layer