Surface modified inorganic fine particles such as silica, titania and alumina are used as external additives to toners in order to enhance the flowability, tribo-electrostatic charge behavior, image property and other performance factors. Due to the adhesion of fumed oxide based additives to the toner surface, the selection of specific external additives has a significant impact on final toner performance. Each external additive has distinctive properties that are affected by diameter, surface conditions, structure, and electric charge. Smaller particles enhance the flowability of the toner. Coating of toner with titania and alumina stabilizes the electrostatic values when charged by friction. This is because, the external additives have a weaker tribo-electrostatic charge and lower electric resistance compared to silica. These inorganic particles are also believed to prevent filming by minimizing the toner impaction process due to enhanced free flow and by polishing the toner adhering to the photo conductor. In this paper, we would like to present an experimental set up to simulate the performance of fumed oxide particles in terms of polishing the filming toner particles.This paper summarizes the influence of various external additives on aspects of toner performance such as flowability, tribo-electrostatic charge (T-ESC) and cleaning properties.