New hafnocene triarylstannyl complexes were prepared and were shown to undergo clean thermal decompositions via alpha-aryl-elimination to produce the corresponding stannylene and a hafnocene aryl complex. The rate of the decomposition is highly dependent on the nature of the ancillary ligand, with the stabilities of the CpCp*Hf(SnPh3)X compounds following the order X = NMe2 > Np (alpha-agostic) > OMe > Cl > Me. Mechanistic information suggests that a-aryl-elimination may be viewed as a concerted process involving nucleophilic attack of the migrating aryl group onto the electrophilic metal center.