Heating of the cyclohexadienyl ruthenium complex [(η 5 -C 6 H 7 )Ru(MeCN) 3 ] + (1) with arenes results in replacement of acetonitrile ligands giving complexes [(η 5 -C 6 H 7 )Ru(arene)] + (arene = toluene, o-xylene, hexamethylbenzene, p-toluidine, benzo-15-crown-5, ethyl ester of N-acetylphenylalanine) in 53–93% yields. Similar reaction of 1 with naphthalene produces labile complex [(η 5 -C 6 H 7 )Ru(naphthalene)] + which readily undergoes solvolysis in acetone. The reaction of 1 with 1,5-cyclooctadiene unexpectedly gives the benzene complex [(η 3 ,η 2 -C 8 H 11 )Ru(C 6 H 6 )] + in 44% yield, as a result of formal abstraction of two hydrogen atoms. Energy decomposition analysis revealed that the cyclohexadienyl ruthenium cation [(η 5 -C 6 H 7 )Ru] + is less arenophilic then [CpRu] + due to weaker orbital interaction with arenes. The structure of [(η 5 -C 6 H 7 )Ru(benzo-15-crown-5)]PF 6 was established by X-ray diffraction.