Abstract: A multilayer liner for a high-pressure gas cylinder is provided. The liner has an impact-modified polyamide (PA) layer in contact with the high-pressure gas. The impact-modified PA layer reduces travel of the high-pressure gas from the inside of the liner to the outside of the liner. Use of a gas barrier layer such as an EVOH layer in combination with the impact-modified PA layer results in improved permeation resistance not heretofore demonstrated in a Type 4 cylinder. Combination of the EVOH layer and the impact-modified PA layer results in an interior surface which is compatible with gas environment in the cylinder, ductility at high pressures, a range of temperatures, and can survive cryogenic conditions.