The influence of thermal pretreatment on the performance of a high-purity limestone (La Blanca) during CO2 capture cycles is investigated in this paper. This limestone was chosen for more detailed investigation because, in earlier research, it failed to show any favorable effect as a result of thermal pretreatment. Here, the original sample, with a particle size of 0.4−0.6 mm, and ground samples were thermally pretreated at 1000−1200 °C, for 6−24 h, and then subjected to several carbonation/calcination cycles in a thermogravimetric analyzer (TGA). This work shows that thermal pretreatment failed to produce a significant self-reactivation effect during CO2 cycles, despite the use of a wide range of conditions during pretreatment (grinding, temperature, and pretreatment duration) as well as during cycling (CO2 concentration and duration of the carbonation stage). Additional doping experiments showed that both high Na content and lack of Al in La Blanca limestone cause poor self-reactivation performance afte...