AbstractSince their discovery in our laboratories as novel photo and thermal initiators for cationic polymerization, diaryliodonium and triarylsulfonium salts have been the object of considerable investigation in our laboratories as well as in a number of other academic and industrial research groups. Recent work in our laboratory has focused on several major themes which will be the topics of this presentation. These include; the synthesis of new photoinitiators with higher photosensitivity, the preparation of polymer bound photoinitiators, the preparation of new cationically polymerizable monomers with high reactivities and lastly, the use of onium salt induced photo and thermally induced cationic polymerization in a number of practical applications.