A nuclear fuel cladding tube for a liquid-metal or molten-salt cooled reactor includes a tubular body of metal material and a protective coating applied on an outer surface of the tubular body, to contact the coolant. The coating includes at least one layer of coating material selected from the group consisting of ceramic materials, refractory metals, and FeCrAlY alloys, and includes a matrix composed of the coating material in amorphous phase, inside which nanodomains composed of the coating material in crystalline phase are dispersed.