Considerable effort has been invested in the development of various methods for the synthesis of hybrid organic/inorganic particles for a variety of applications. Not enough attention has been given to the use of such particles as starting reagents for chemical reactivity studies and for further chemical modifications. The complexity of such reactivity, dictated by the architecture and composition of the hybrid particles, is demonstrated here for the addition reactions of iodine and bromine with linear polyisoprene@silica and cross-linked polyisoprene@silica sub-micron particles, in both water (hydrohalogenations) and CCl₄ (halogen additions). The reactivities of these new particles were comparatively studied, and correlated to the differences between the two types of particles as revealed by electron microscopy, zeta potential measurements, thermal gravimetric analysis, surface area measurements, non-reactive intra-particle diffusion, and more.