A barrier structure selected from bottles, tanks, containers, pipes, recipients and films comprising at least one fuel barrier layer comprising an MXDT/XT copolyamide wherein: MXDT is a unit with an amide motif present at a molar level ranging from 5 to 45%, preferably from 15 to 45%, more preferentially from 20 to 45%, where MXD represents m-xylylene diamine and T is terephthalic acid, XT is a unit with majority amide motif present at a molar level ranging from 55 to 95%, preferably from 55 to 85%, more preferentially from 55 to 80%, where X is a C9 to C18 linear aliphatic diamine, preferably C9, C10, C11 or C12 and where T is terephthalic acid, said copolyamide having a melting temperature: 250°C < T m ≤ 300°C as determined according to ISO 11357-3, - in the MXDT and/or XT units, independently of one another, up to 30 mol%, relative to the total amount of the dicarboxylic acids, the terephthalic acid may be replaced by other aromatic, aliphatic or cycloaliphatic dicarboxylic acids having 6 to 36 carbon atoms, in particular 6 to 14 carbon atoms, and - in the MXDT and/or XT units, independently of one another, up to 30 mol% of the MXD and/or according to the case of X, relative to the total amount of diamines, may be replaced by other diamines having 4 to 36 carbon atoms, in particular 6 to 12 carbon atoms, and - in the copolyamide, not more than 30 mol%, relative to the total quantity of the monomers, can be formed by lactams or aminocarboxylic acids, and - provided that the sum of the monomers that replace the terephthalic acid, the MXD and X does not exceed a concentration of 30 mol% relative to the total quantity of monomers used in the copolyamide, and - provided that the MXD is not fully substituted, said structure being devoid of reinforcing fibers, and wherein a second layer is present, layers and being capable of adhering to each other, said layer comprising at least one polyamide chosen from an aliphatic polyamide and an aromatic polyamide, in particular an aliphatic polyamide and said barrier layer is in contact with the fluid. MXDT is a unit with an amide motif present at a molar level ranging from 5 to 45%, preferably from 15 to 45%, more preferentially from 20 to 45%, where MXD represents m-xylylene diamine and T is terephthalic acid, XT is a unit with majority amide motif present at a molar level ranging from 55 to 95%, preferably from 55 to 85%, more preferentially from 55 to 80%, where X is a C9 to C18 linear aliphatic diamine, preferably C9, C10, C11 or C12 and where T is terephthalic acid, said copolyamide having a melting temperature: 250°C < T m ≤ 300°C as determined according to ISO 11357-3, - in the MXDT and/or XT units, independently of one another, up to 30 mol%, relative to the total amount of the dicarboxylic acids, the terephthalic acid may be replaced by other aromatic, aliphatic or cycloaliphatic dicarboxylic acids having 6 to 36 carbon atoms, in particular 6 to 14 carbon atoms, and - in the MXDT and/or XT units, independently of one another, up to 30 mol% of the MXD and/or according to the case of X, relative to the total amount of diamines, may be replaced by other diamines having 4 to 36 carbon atoms, in particular 6 to 12 carbon atoms, and - in the copolyamide, not more than 30 mol%, relative to the total quantity of the monomers, can be formed by lactams or aminocarboxylic acids, and - provided that the sum of the monomers that replace the terephthalic acid, the MXD and X does not exceed a concentration of 30 mol% relative to the total quantity of monomers used in the copolyamide, and - provided that the MXD is not fully substituted, - in the MXDT and/or XT units, independently of one another, up to 30 mol%, relative to the total amount of the dicarboxylic acids, the terephthalic acid may be replaced by other aromatic, aliphatic or cycloaliphatic dicarboxylic acids having 6 to 36 carbon atoms, in particular 6 to 14 carbon atoms, and - in the MXDT and/or XT units, independently of one another, up to 30 mol% of the MXD and/or according to the case of X, relative to the total amount of diamines, may be replaced by other diamines having 4 to 36 carbon atoms, in particular 6 to 12 carbon atoms, and - in the copolyamide, not more than 30 mol%, relative to the total quantity of the monomers, can be formed by lactams or aminocarboxylic acids, and - provided that the sum of the monomers that replace the terephthalic acid, the MXD and X does not exceed a concentration of 30 mol% relative to the total quantity of monomers used in the copolyamide, and - provided that the MXD is not fully substituted, said structure being devoid of reinforcing fibers, and wherein a second layer is present, layers and being capable of adhering to each other, said layer comprising at least one polyamide chosen from an aliphatic polyamide and an aromatic polyamide, in particular an aliphatic polyamide and said barrier layer is in contact with the fluid.