The incorporation of OH-defects in quartz, coesite and stishovite, synthesized at temperatures between 900 and 1100C and pressures ranging from crustal (5 kbar, i.e., 0.5 GPa) to upper mantle depths (9.1 GPa), was investigated. All silica polymorphs were grown in a water-saturated granitic system, which was doped in different amounts of Li, B and P by adding spodumene, tourmaline or apatite in the starting mixtures. The experimental products were successively analyzed by IR spectroscopy, electron microprobe, LA-ICP-MS and SIMS. <br />All IR absorption spectra in quartz revealed one dominant triplet band at 3431, 3379 and 3313 cm-1 and a less intense band at 3585 cm-1, assigned to AlOH- and hydrogarnet-defects, respectively. Additionally, quartz grown in the Li- and B- systems exhibited two supplementary bands at 3483 cm-1 and 3595 cm-1, related to LiOH- and BOH-defects, respectively. Both AlOH and LiOH concentrations decreased with pressure, until no LiOH-defects were detected at pressure higher than 15 kbar. The most pronounced decrease of these hydrous defects occurred in a rather narrow pressure interval (10-15 kbar) close to the high-quartz/low-quartz transition, but no real link was found between the transition and the defect incorporation. The simultaneous presence of dry AlLi-defect was further suggested, due to higher total Li concentrations than Li coupled with LiOH. <br />On the other hand, no hydrous defects were observed in coesite synthesized at 4 GPa, whereas coesite grown at higher pressures revealed a triplet band at 3575, 3523 and 3459 cm-1, two minor bands at 3535 and 3502 cm-1, and a small band at 3300 cm-1 that was only visible at 7.7 GPa. The triplet was strongly correlated to the aluminum content, suggesting an assignment as AlOH-defects, while the two minor bands were assigned to BOH-defects, and the band at 3300 cm-1 was interpreted as interstitial H. Stishovite displayed one dominant band at 3116 cm-1 with a shoulder at 3170 cm-1, and a minor band at 2665 cm-1, probably all associated to AlOH-defects. BOH-defects were not observed in stishovite, and LiOH-defects were neither observed in coesite nor stishovite, probably because of preferentially partition of Li in other phases such as omphacite. The total amount of hydrous defects in high pressure silica polymorphs increased with pressure, in contrast to the negative trend of OH in quartz against pressure, and revealed a minimum concentration of OH around the quartz/coesite phase transition.