High-surface-area samples of strontium oxide, prepared by thermal decomposition of high-purity SrCO3in vacuo, have been examined for their reactivity and/or catalytic activity towards molecular gas probes and their luminescence spectra have been recorded. Temperature profiles are reported, as a function of prior outgassing temperature, for the development of room-temperature excitation and emission spectra. These are compared with temperature profiles for the development of room-temperature catalytic activity for R0-type oxygen isotope exchange, 16O2+18O2⇌ 216O18O, and for the development of activity for nitrous oxide decomposition at various temperatures. Consideration is given to interpretations of the results in terms of ions at coordinatively unsaturated surface locations, to the extent to which these are exposed after thermal activation at various temperatures and to the involvement of point defects in the surface locations responsible for the various surface processes.