SnCl2 is dissociated to SnCl and Cl by absorption of light in the 320 nm region. This sets a maximum value to the dissociation energy of SnCl2. Further consideration of thermochemical and spectroscopic data gives the probable values of the dissociation energies of SnCl2 and SnCl as 370 ± 20 and 420 ± 20 kJ mol–1 respectively. SnCl2, SnCl, and Sn are observed during the flash photolysis of SnCl4. SnCl2 is produced by decomposition of vibrationally excited SnCl3 formed in the primary photolysis. SnCl is produced by secondary photolysis of SnCl2 and reacts with SnCl4 at a rate approaching the encounter rate. Sn also reacts rapidly with SnCl4.