A new and easy method for preparing blue sodalite pigments which involves high-temperature calcination of sodalite samples synthesized with aluminum sulfate and an organic template, is presented. Calcination generated the S-3(-) and S-2(-) radicals, and the effects of the Al/Si ratio and the calcination temperature on the nature and amounts of the radicals were examined. The radicals were characterized in detail by continuous wave and pulsed EPR at X- and W-band frequencies (similar to9 and 95 GHz, respectively) complemented by UV-vis measurements. The high-field electron-paramagnetic resonance (EPR) measurements allowed us to clearly resolve the g anisotropy of S-3(-) and W-band electron nuclear double resonance (ENDOR) measurements detected strong coupling with extra-framework Na-23 cations and weak coupling with framework Al-27. On the basis of the spectroscopic results and density functional theory (DFT) calculations of the g-tensors of S-3(-) and S-2(-) radicals, the EPR signals were attributed to three different S-3(-) radicals, all with the open structure C-2v, that are located within the sodalite beta cages. While two of these radicals are well isolated, the third one is associated with an exchange-narrowed signal originating from S-3(-) radicals in nearby sodalite cages.