  Compact symmetric objects conform a class of sources characterized by high
luminosity radio emission located symmetrically on both sides of the active
galactic nucleus on linear scales of less than 1 kpc. Given their small size,
the hot spots of the jets in CSOs provide a unique laboratory for the study of
the physics of relativistic jets and their environment close to the central
engine.
  We present a simple model for the hot spots in CSOs assuming synchrotron
emission, minimum energy and ram pressure equilibrium with the external medium.
Further comparison of our model with observational data allows us to constrain
the physical parameters in the hot spots and the jets feeding them, and the
density profile of the external medium.
