Method for the production, by means of rotational molding, of a boss-liner structure for a type IV pressure vessel from a material containing a curable raw material, comprising the steps of: ▪ providing a mold, for forming a liner comprising a hollow body defined by an elongated cylindrical liner wall having opposed inner and outer surfaces extending between a first end and a second end of the liner, wherein the cylindrical liner wall comprises a cylindrical main portion, a rounded head portion and a neck-shaped end section , wherein the cylindrical liner wall has a passage opening near the first end of the liner, wherein the passage opening is determined by an edge of the liner; ▪ providing a boss having a boss bore extending axially through the boss, wherein the boss bore is determined by a cylindrical wall having an inner surface, and a flange projecting radially outward having inner and outer flange surfaces located opposite to each other, wherein the boss is arranged so that the bore at least partially extends into an interior of the mold, and so that the outer flange surface faces the inner surface of the mold; ▪ providing a sealing element in the boss bore through the boss; characterized in that the method comprises the steps of: ▪ filling a mold cavity in the mold with a first thermoplastic material; ▪ heating the material to a first predetermined temperature; ▪ rotating the mold so that an outer monolithic layer of the liner is formed from the first thermoplastic material, wherein the liner is formed at the inner and outer sides of the flange and in bores or recesses of the flange and wherein the flange is integrated into the outer monolithic layer; ▪ forming at least one further layer of the liner inside the outer monolithic layer, such that the liner is a layered liner consisting of a plurality of monolithic layers of at least two different thermoplastic materials; and ▪ cooling the formed liner to a second predetermined temperature. ▪ providing a mold, for forming a liner comprising a hollow body defined by an elongated cylindrical liner wall having opposed inner and outer surfaces extending between a first end and a second end of the liner, wherein the cylindrical liner wall comprises a cylindrical main portion, a rounded head portion and a neck-shaped end section , wherein the cylindrical liner wall has a passage opening near the first end of the liner, wherein the passage opening is determined by an edge of the liner; ▪ providing a boss having a boss bore extending axially through the boss, wherein the boss bore is determined by a cylindrical wall having an inner surface, and a flange projecting radially outward having inner and outer flange surfaces located opposite to each other, wherein the boss is arranged so that the bore at least partially extends into an interior of the mold, and so that the outer flange surface faces the inner surface of the mold; ▪ providing a sealing element in the boss bore through the boss; ▪ filling a mold cavity in the mold with a first thermoplastic material; ▪ heating the material to a first predetermined temperature; ▪ rotating the mold so that an outer monolithic layer of the liner is formed from the first thermoplastic material, wherein the liner is formed at the inner and outer sides of the flange and in bores or recesses of the flange and wherein the flange is integrated into the outer monolithic layer; ▪ forming at least one further layer of the liner inside the outer monolithic layer, such that the liner is a layered liner consisting of a plurality of monolithic layers of at least two different thermoplastic materials; and ▪ cooling the formed liner to a second predetermined temperature. <EOS>