The higher n-alkyl hydrides [W{(η-C 5 H 4 )CMe 2 (η-C 5 H 4 )}(R)H](R={(CH 2 ) n CH 3 }, n=1–4) and the isotopically labelled analogues [W(η-C 5 D 4 )C(CD 3 ) 2 (η-C 5 D 4 )}(R)D], (R={(CH 2 ) n CH 3 } (n=1–4) and [W{(η-C 5 H 4 )CMe 2 (η-C 5 H 4 )}{CD 2 CD 3 }H] have been prepared and the hydrogen/deuterium exchange processes under thermal conditions in these compounds have been investigated by NMR spectroscopy. In every case of all the possible alkyl hydrogens of the alkyl groups R only H/D exchange with the α-CH 2 methylene hydrogens was observed.