Abstract: A process for increasing the activity of a zeolite-containing particulate solid containing contaminants which block the pores of the zeolite and adversely affect the activity thereof wherein the contaminated zeolitic material is slurried with a liquid containing an acid, detergent or surfactant, the slurry is agitated to liberate the pore-blocking contaminants from the zeolite pores so that they are suspended in the liquid, a portion of the liquid is withdrawn from the slurry and filtered to remove the suspended contaminants, the resulting liquid is returned to the slurry, and the treated zeolite-containing particulate solid is liquid from the solution and recovered.