The reaction kinetics of the decomposition of 1-methylsilacyclobutane (MSCB) in a hot wire chemical vapor deposition (HWCVD) reactor was investigated. The stable reaction products were monitored using a vacuum ultraviolet laser single photon ionization in tandem with time-of-flight mass spectrometry. Steady-state approximation was used to determine the rate constants of three individual decomposition pathways of MSCB, i.e., cycloreversion to form ethene and methylsilene (R1), ring opening to form propene and methylsilylene (R2), and exocyclic Si-CH₃ bond cleavage to form ·CH₃ radical (R3). The activation energies (Ea) for R2 and R3 in a HWCVD reactor were determined to be 86.6 kJ·mol^-1 and 106 kJ·mol^-1, respectively. The fact that these Ea values are close to those obtained for the MSCB decomposition on metal surfaces under collision-free conditions indicates that the heterogeneous reactions on the hot wire surface govern the gas-phase reaction kinetics in the HWCVD reactor. In addition, the Ea values of R1, R2, and R3 obtained from a theoretical study of the decomposition kinetics using ab initio calculations at the CCSD(T)/6-311++G(3d,2p)//MP2/6-311++G(d,p) level of were 62.9 kcal·mol^-1 (i.e., 263 kJ·mol^-1), 62.0 kcal·mol^-1 (i.e., 259 kJ·mol^-1), and 86.2 kcal·mol^-1 (i.e., 361 kJ·mol^-1) for R1, R2 and R3, respectively. The much lower experimental Ea values compared to those from the theoretical calculations clearly suggest that tungsten filament in the HWCVD reactor catalyzed the decomposition.