General interest in the use of cationic photopolymerization instead of free-radical photopolymerization for preparation of polymer coatings is still growing. This generates the need for better understanding of the subtle nuances of this method and the need for development of new, more efficient one-component cationic photoinitiators, because the photopolymerization speed depends on their performance. This chapter presents the structural and kinetic aspects of using the new one-component photoinitiators for cationic photopolymerization processes of monomers. Especially, long-wavelength cationic photoinitiators are discussed because they have attracted growing interest owing to the wide applications of LED sources.