A study of electron-impact induced processes of thirty substituted styrenebis(tricarbonyliron) complexes XC 6 H 4 C(R α)=CR β [Fe(CO) 3] 2, and of some ten corresponding styrene free ligands is described. All the mass spectra of the organoiron complexes are characterized by the consecutive losses of carbon monoxide followed by loss of one or tow iron atoms: [LFe 2(CO) 6] +. (a) LFe +. 2 (c) LFe +. (g) L + Depending on the nature of the substituent, X, and its position on the styrene ligand, the organic moiety in LFe + ruptures in four main modes: ( d) loss of neutral methane when X = H, CH 3, C 6H 5, CH 3O and F; R α = CH 3 and R β = H; ( e) loss of neutral acetylene when X = H, CH 3O; R α = H and R β = CH 3; ( f) loss of HX when X = halogen, R α = H, CH 3 and R β = H; ( g) loss of iron. In the halogen-containing organoiron complexes, the ionic fragment LFe +. 2 predominates in the mass spectra. It is characterized by its tendency to lose a neutral alkyne molecule to yield the corresponding ionic fragment of diiron—halogenobenzene [mode ( b)]. Unlike the organoiron complexes which eject neutral molecules, the corresponding free ligands tend to lose mainly radical species. The preparation and properties of nine hitherto unreported styrene—bis(tricarbonyliron) complexes are described.