Ignition delay times of tetraethoxysilane (TEOS) mixtures diluted with dry and humid synthetic air were measured behind reflected shock waves by monitoring the chemiluminescence emission of the CH* radical near 431 nm. The measurements were carried out for temperatures ranging from 1150 to 1350 K and an average pressure of 8 bar. The ignition-delay times of TEOS were determined as a function of water concentration. Additionally, TEOS stability in presence of humid air was investigated by means of Fourier transform infrared spectroscopy (FTIR) to insure that the mixture does not react prior to shock-wave heating. The results show that the stability of TEOS is not affected under the experimental conditions but that the presence of moisture in the TEOS/air mixture increases the ignition-delay times systematically.