The reversible gas-solid thermochemical reaction between CO2 and SrO to form SrCO3 is considered for storing high-temperature heat delivered by concentrated solar energy systems. To maintain cycling stability, MgO-stabilized SrO-based materials were synthetized with various precursors and support contents by the co-precipitation, sol-gel, wet-mixing and dry-mixing production methods. Samples were analysed by thermogravimetry over multiple consecutive carbonation-calcination cycles in the range of 1000-1100 degrees C. The best performance was obtained by using the wet-mixing method with strontium acetate hemihydrate and porous magnesium oxide as precursors: the formulation with 40 wt% SrO featured stable chemical conversion over 100 consecutive carbonation-calcination cycles at 1000 degrees C and yielded gravimetric energy density of 0.81 MJ/kg.