Vacuum ultraviolet (VUV) photoionization at 10.2 eV was employed for the detection of gas-phase molecules formed after thermal decomposition of disilane at a total pressure of 30 Torr and in the temperature range of 298-740 K. The SinH2(n+1) (n = 3-5) and SinH2n (n = 2-5) species resulting from disilane pyrolysis in a flow reactor were directly observed using time-of-flight mass spectrometry. Unlike multiphoton ionization at 6.4 eV photons, no fragmentation was observed by the VUV single-photon ionization at 10.2 eV.