Gaseous HCl and Cl 2 as well as CoCl 2 6H 2 O and KI dissolved in methanol were added to fullerene-forming flat benzene/oxygen/argon flames burning at 75 mbar. The soot formed in the flames was collected and analysed by mass spectrometry using chemical ionization with CH 4 /N 2 O. In the case of HCl or Cl 2 addition no formation of halogenated fullerenic compounds was observed, while the measurement of chlorine precursor mass spectra showed the formation of a great number of chlorine-containing compounds, essentially polycyclic aromatic hydrocarbons (PAHs). The addition of CoCl 2 6H 2 O led to the formation of C 6 0 OHCl by means of ion-molecule reactions in the flame. After addition of CoCl 2 6H 2 O or KI, molecular masses corresponding to metal fullerene compounds like CoC 5 8 , CoC 8 4 , CoC 9 2 and COC 1 3 4 or K 2 C 5 6 and K 2 C 6 6 were observed.