The kinetics of the reactions of Br[4p(²P_J)] with CH₃SiH₃(1) and (CH₃)₂SiH₂(2) have been measured using flash photolysis/time-resolved atomic resonance spectroscopy over the temperature ranges 350–550 and 390–550 K, respectively. The results are k₁=(4.0 ± 0.5)× 10^–10 exp(–19.7 ± 0.5 kJ mol^–1/RT) and k₂=(4.3 ± 0.8)× 10^–10 exp(–21.6 ± 0.7 kJ mol^–1/RT) in units of cm³ s^–1, with confidence limits of ca.±13%. Assumed activation energies for the reverse reactions yield Si—H bond dissociation enthalpies, D₂₉₈, of 388 ± 5 and 392 ± 5 kJ mol^–1 in methylsilane and dimethylsilane, respectively. These values and the Arrhenius parameters are intermediate between earlier results for Br + SiH₄ and Br +(CH₃)₃SiH, although the uncertainty in D₂₉₈ is too great to establish a firm trend in D₂₉₈ with the degree of methylation. The silanes and corresponding silyl radicals are characterized by ab initio methods at up to the MP4/6-31G*//HF/6-31G* level.