Relativistic extended thermodynamics from the Lagrangian view-point

The salient points of Relativistic Extended Thermodynamics (R.E.T.) are here revised according to the Lagrangian view-point: Attention is focused to each material particle and to its physical properties, during all the motion of the same particle. The results for the non relativistic case are already present in literature. Here a similar procedure is followed for R.E.T. with an arbitrary number of moments. It is also shown how the Einstenian Relativity Principle and some symmetry condition, which are present in the Eulerian view-point, can be "translated" in the Lagrangian view-point, where they are no more so self-evident.