Dissociative ionization of Si(CH3)Cl-3 has been investigated by photoionization mass spectrometry and calculations of molecular electronic structure. From the photoionization efficiency spectra of ions measured over an energy range 9-30 eV, we determined appearance energies of the parent cation and various fragment cations. The ionization energy of Si(CH3)Cl-3 is 11.18 eV. A fragment SiCl3+ appears at 11.77 eV and a second fragment Si(CH3)Cl-2(+) at 12.02 eV. Molecular electronic calculations of structures and energies of the Si(CH3)Cl-3(+) radical cation and various fragment cations are made with GAUSSIAN-2 and GAUSSIAN-3 in the GAUSSIAN 98 package. Reaction energies for various fragmentation processes are computed, in satisfactory agreement with experimental data for dissociation. Results of these calculations are applied to establish dissociative photoionization channels of Si(CH3)Cl-3 near the ionization threshold. (C) 2003 American Institute of Physics.