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This work focused on enhancing the CO2 capture kinetics of magnesite-derived MgO via alkali nitrate and mineral CaCO3 promoters for its application in the Carbonate Looping technology at intermediate temperatures (≤400°C). Alkali salts had a prominent role by shifting into molten state to offer a favorable carbonation pathway and allow a significantly higher CO2 uptake than non-promoted MgO, while their synergy with CaCO3 bestowed even better sorption activity. MgCO3 and CaMg(CO3)2 were detected as the main carbonate products, with the latter exhibiting faster formation rate. The sorbent with CaCO3 and alkali salts to MgO molar ratios of 0.05 and 0.20 respectively attained an uptake of 7.2 moles CO2/kg of sorbent when exposed to a 30%CO2 flow at 300°C with only 6% activity loss after 50 carbonation cycles, proving the applicability of the materials. Despite the cyclic sorption activity loss due to sintering and dewetting, alkali salts redistribution enabled a stable performance under proper conditions.