Composition of catalyst for purifying exhaust gases.

A catalyst composition disposed on a base comprising a mixture of: (a) a composite oxide particles comprising ceria, zirconia and samaria; (B) a catalytically effective amount of at least one component of a precious metal, and (c) a refractory metal oxide support particles, said material being present compound in an amount of from 0.0006 to 0.18 g / cm 3 of the base.