In situ infrared absorption spectroscopy is used to monitor atomic layer deposition (ALD) of aluminum oxide (Al2O3) on carboxylic acid-terminated self-assembled monolayers (SAMs), Si(III)-(CH2)10-COOH (or COOH-SAMs), directly grafted on silicon (111) at similar to 100 degrees C. The quality of resulting Al2O3 films is comparable to Al2O3 on SiO2. Both the SAM film and the Si/SAM interface remain chemically stable during growth and upon post annealing to 400 degrees C, Suggesting that the tight packing of the alkyl chains and COOH-SAM head groups presents a diffusion barrier and promotes ordered nucleation for ALD.