Ignition and reaction kinetics of silane/oxygen/diluent (SiH4/O-2/Ar/N-2) mixtures have been studied using a rapid compression facility (RCF). Time-resolved pressure profiles and absolute, quantitative hydroxyl radical mole fraction (χ(OH)) time histories were obtained for a range of conditions representing different heating rates. At the moderate temperatures studied (∼ 630 K), ignition was observed to occur in two stages with no OH detected during the first stage. The separation of the two stages was typically > 5 ins, thus the long test times provided by the RCF were critical to the studies. The second stage of reaction is identified by significant production of OH (χ(OH) = 45-82 ppm). Experimental uncertainty in χ(OH) was 32/-29 % with a 15 ppm detectivity limit. The results were examined in the context of proposed silane combustion and particle nucleation reaction mechanisms. Existing silane combustion kinetics mechanisms capture many of the experimentally observed features of the system, yet fail to quantitatively reproduce the OH time histories in their entirety. © 2005 The Combustion Institute. Published by Elsevier Inc. All rights reserved.