The use of catalytic nanoparticle additives in composite solid propellant as burning rate modifiers has received much research attention in recent years, and as the widespread application of nanoparticles becomes more practical, scale-up processing and testing will be required. This article investigates the potential benefits of various additive processing methods and their effects on the burning rate of propellant consisting of ammonium perchlorate and hydroxyl terminated polybutadiene. Titania was investigated herein, but many of the results should apply to any metal oxide catalyst. Depending on how the additive was processed, it was seen to be both an effective and ineffective burning rate modifier. The ideal processing method was determined, leading to a better understanding of how the additive interacts with the propellant. The physical properties of the additive agglomerations were found to be a link between the additive processing and its effectiveness. Specifically, sintering of the additive agglomerates during heat treating limited the dispersion of the additives, ultimately hindering their ability to modify burning rate. This article presents one of the first studies that conclusively demonstrates the link between the processing of nanoparticles and their effectiveness in modifying propellant burning rate.