A systematic approach was used to select metal oxides with varying composition, surface chemistry and particle size, which were then blended on toner particles as surface additives. The Hosokawa Powder Flow tester was used to study the toner cohesion, both as initially blended, and with aggressive toner aging. The toner powder flow cohesion and aging was studied for two different base toner particles, based on a styrene/acrylate resin and a polyester resin. It is shown that selection of the metal oxide size, oxide type and chemistry is important to ensure stable flow with aging time.