The methylsilylidyne (SiCH 3 , X 2 A″) and the silenyl (H 2 CSiH, X 2 A′) radicals were identified via infrared spectroscopy in low temperature silane–methane matrices upon irradiation of the samples matrices with energetic electrons at 10K. The ν 4 and ν 3 fundamentals of the methylsilylidyne species were detected at 1226 and 1371cm −1 , whereas one band of the silenyl radical showed up at 822cm −1 (ν 6 ). These assignments were verified in partially deuterated matrices. Our studies suggest that these radicals are generated through radiolysis of silene (H 2 CSiH 2 , X 1 A 1 ) and its methylsilylene isomer (CH 3 SiH, X 1 A′). The new absorptions of two SiCH 3 isomers can be utilized in future spectroscopic studies of chemical vapor deposition processes and in astronomical searches of silicon-bearing organometallic molecules to better understand the chemistry of the circumstellar envelope of the carbon star IRC+10216.