Abstract: A method of production of a cladding tube for a nuclear fuel element wherein a first hollow billet of a zirconium alloy and a second hollow billet of zirconium having a smaller outer diameter than the first hollow billet are formed by heat treatment, forging and cutting. A resilient member is inserted in a space defined between the first hollow billet and the second hollow billet inserted in the first hollow billet, a pressure oriented axially of the two hollow billets is applied to the resilient member to bring the outer wall surface of the second hollow billet into intimate contact with the inner wall surface of the first hollow billet, and opposite ends of the two hollow billets are joined and sealed. The hollow billets thus joined into a unitary structure are subjected to hot extrusion, cold working and heat treatment to produce a composite tube of reduced diameter and reduced thickness, and the inner and outer wall surfaces of the composite tube are ground.