Direct oxidation processes, such as ethylene epoxidation to ethylene oxide, have been researched extensively due to their commercial significance. Despite the importance of epoxide production, the mechanistic details of olefin epoxidation remained obscure until recently and the majority of significant advances in Ag-catalyst development occurred primarily through empirical methods. Recent surface science studies of ethylene oxide and 1-epoxy-3-butene have identified an oxametallacycle species as the active intermediate in Ag-catalyzed epoxidation of both ethylene and 1,3-butadiene; expansion of the epoxide ring to incorporate surface silver atoms forms the oxametallacycle species. Oxametallacycles have been isolated by ring-opening ethylene oxide, 1-epoxy-3-butene, and styrene oxide on Ag(111) and 1-epoxy-3-butene on Ag(110). Surface science techniques and density functional theory were used in this study to investigate the interactions of styrene oxide and isoprene oxide with Ag-surfaces. In agreement with previous studies of olefins on Ag(110) and Ag(111), these complex epoxides undergo activated ring-opening to form stable surface species on silver; these intermediates reform their parent epoxides during subsequent temperature-programmed desorption. Because the molecular forms of both styrene oxide and isoprene oxide desorb molecularly from silver below 250 K, the intermediate species derived from the these epoxides are most likely surface oxametallacycles. Preliminary density functional theory calculations predict that cleavage of the epoxide ring occurs at the carbon bearing the substituent group to form surface oxametallacycle intermediates.