CH2=Si(CH3)OSi(CH3)2+ ions 1 were formed in the external source of a Fourier-transform ion cyclotron resonance (FT-ICR) mass spectrometer by fragmentation of (CH)3SiOSi(CH3)3. In the cell, their reactions with acetaldehyde were studied by using labeled reactants and compared with those with acetone, studied in previous work, which gives a general view of the reactions of ion 1 with carbonyl compounds. In contrast with the behavior of the corresponding carbon-containing ions, the results confirm facile 1,3-methyl group transfers from silicon to silicon. Otherwise, the silicon-containing adducts often eliminate CnH2n. This process, not observed in (C,O,H)-containing ions, is studied by using selectively deuterated reactants.