The thermal decomposition of dimethylaluminum isopropoxide dimer, [(CH 3 ) 2 Al(O i C 3 H 7 )] 2 , on Si(100) is investigated by line-of-sight temperature programmed desorption (LOS-TPD), line-of-sight isothermal reaction spectroscopy (LOS-IRS), and Auger electron spectroscopy (AES). [(CH 3 ) 2 Al(O i C 3 H 7 )] 2 does not decompose upon adsorption on Si(100) held at 100K or during subsequent LOS-TPD. AES indicates that film growth starts when the precursor is dosed with the substrate at ~650K. LOS-IRS shows that the monomer, [(CH 3 ) 2 Al(O i C 3 H 7 )] 2 , is an intermediate in the process of the dimer decomposition to aluminum-containing films, and that further decompositions occur via breaking the C Al and O C bonds.