  Starting from a formulation for the $dS$ element that includes movement, and
considering the variation of the entropy Lorentz invariant, we found the
relativistic transformations for thermodynamic systems that satisfy the three
laws of thermodynamics. Particularly, we found the temperature and pressure
transformations, given by $T'=\gamma T$ and $p'=\gamma^2p$ respectively.
Furthermore, we show that this transformations keeps the form of the state
equation for an ideal gas in agreement with the relativity principle.
