Organophosphonic acid self-assembled monolayers (SAMs) on oxide surfaces have recently seen net eased use in electrical and biological sensor applications The reliability and reproducibility of these sensors require good molecular organization in these SAMs In this regard, packing, order, and alignment in the SAMs is important, as it influences the electron transport measurements In this study. we examine the order of hydroxyl- and methyl-terminated phosphonate films deposited onto silicon oxide surfaces by the tethering by aggregation and growth method using complementary. state-of-art surface characterization tools Near-edge X-ray absorption fine structure (NEXAFS) spectroscopy and in situ sum frequency generation (SFG) spectroscopy ale used to study the older of the phosphonate SAMs in vacuum and under aqueous conditions, respectively X-ray photoelectron spectroscopy and time-of-flight secondary ion mass spectrometry results show that these samples form chemically intact monolayer phosphonate films NEXAFS and SFG spectroscopy showed that molecular order exists in the octadecylphosphonic acid and 11-hydroxyundecylphosphonic acid SAMs. The chain till angles in these SAMs were approximately 37 degrees and 45 degrees, respectively