Submicron silicas produced by hybrid process and their corresponding surface-modified counterparts are compared with respect to their applicability as external additives for electrophotographic toners. The principal metric for comparison is triboelectrostatic charge (T-ESC) stability under extended activation periods. Experimental samples are surface-modified submicron silicas produced by a hybrid process. The hybrid materials have sufficient hydrophobicity and can work as spacer particles to prevent the embedding of small particle size external additives. Further characteristics and advantages for this new external additive type will be presented. The surface modification improves charge stability and the spacer effect, especially under extreme environmental conditions, that can impact toner performance.