The hydrosilylation of allyl compounds is very important for the industrial production of gamma-substituted propylsilanes; however, it is also a process known to suffer from either substantial selectivity issues or short catalyst lifetimes. While there are reports on the platinum-catalyzed variant, this study is the first comprehensive work on the more recently employed iridium-catalyzed process. A combination of stoichiometric and catalytic experiments as well as reactions with isotope-labeled compounds is used to elucidate the critical parameters influencing the catalytic performance and to identify the main deactivation pathways. This report is intended to pave the way toward the optimization of current iridium-catalyzed processes and the design and synthesis of improved catalyst structures. (C) 2015 Elsevier Inc. All rights reserved.