We report new century-scale ice core records of hydrogen peroxide (H2O2), a major atmospheric oxidant, from 23 locations across the West Antarctic Ice Sheet (WAIS) and use the spatial variability of (multi-) annual mean H2O2 concentrations in snow and firn to investigate the sensitivity of ice core H2O2 preservation to mean annual temperature and accumulation rate. In agreement with the ice-air equilibrium partitioning, H2O2 uptake in near-surface firn was found to be greatest at low temperatures, while postdepositional losses from degassing increase as accumulation rates decrease. This resulted in almost complete loss of H2O2 at warm (>-25¿C), low-accumulation sites (94% deviations from the ice-air equilibrium at high-accumulation sites (>30 cm yr-1), but close-to-equilibrium values on the East Antarctic Plateau, where it is dry ( 0.6, p 30 cm yr-1) are most suitable for detection of temporal changes in atmospheric concentration, although a long-term H2O2 record will be well preserved under the current environment at the WAIS Divide core site.