A NOx storage component comprises caesium silicate (Cs2SiO3) and at least one platinum group metal. The invention also includes a NOx absorber catalyst comprising a NOx storage component according to the invention disposed on a substrate monolith; a method of treating exhaust gas containing NOx from a lean burn internal combustion engine comprising the steps of contacting a NOx storage component comprising caesium silicate (Cs2SiO3) and at least one platinum group metal with lean exhaust gas containing NOx to adsorb NOx thereon; and periodically desorbing adsorbed NOx by contacting the NOx storage component vent with stoichiometric or rich exhaust gas; and a method of making a NOx storage component according to the invention comprising the steps of combining and reacting an aqueous salt of at least one platinum group metal, an aqueous caesium salt and a source of silica.