Threshold photoelectron-photoion coincidence spectroscopy (TPEPICO) has been used to study the dissociation kinetics and thermochemistry of Me4Si, Me6Si2, and Me3SiX, (X = Br, I) molecules. Accurate 0 K dissociative photoionization onsets for these species have been measured from the breakdown diagram and the ion time-of-flight distribution, both of them analyzed and simulated in terms of the statistical RRKM theory and DFT calculations. The average enthalpy of formation of trimethylsilyl ion, Delta fH degrees(298K)(Me3Si+) = 617.3 +/- 2.3 kJ/ mol, has been determined from the measured onsets for methyl loss (10.243 +/- 0.010 eV) from Me4Si, and Br and I loss from Me3SiBr (10.624 +/- 0.010 eV) and Me3SiI (9.773 +/- 0.015 eV), respectively. The methyl loss onsets for the trimethyl halo silanes lead to Delta H-f degrees(298K)(Me2SiBr+) = 590.3 +/- 4.4 kJ/mol and Delta H-f degrees(298K)(Me5Si2+) = 487.6 +/- 6.2 kJ/mol. The dissociative photoionization of Me3SiSiMe3 proceeds by a very slow Si-Si bond breaking step, whose rate constants were measured as a function of the ion internal energy. Extrapolation of this rate constant to the dissociation limit leads to the 0 K dissociation onset (9.670 +/- 0.030 eV). This onset, along with the previously determined trimethylsilyl ion energy, leads to an enthalpy of formation of the trimethylsilyl radical, Delta H-f degrees(298K)(Me3Si center dot) = 14.0 +/- 6.6 kJ/mol. In combination with other experimental values, we propose a more accurate average value for Delta H-f degrees(298K)(Me3Si center dot) of 14.8 +/- 2.0 kJ/mol. Finally, the bond dissociation enthalpies (Delta H-298K) Si-H, Si-C, Si-X (X = Cl, Br, I) and Si-Si are derived and discussed in this study.