In this report, in order to establish energy-saving and low-cost CCU technology, we propose a CCU process in which a CO₂-rich chemical absorbent is directly hydrothermally treated to simultaneously synthesize organic compounds such as formic acid and regenerate and reuse the absorbent. Preliminary experiments of formic acid synthesis by hydrothermal treatment of potassium hydrogen carbonate (KHCO₃) aqueous solution as a CO₂ source were carried out using Ni powder as a catalyst and Fe powder as a reductant. After 2 hours heating at 300℃, the 1 M KHCO₃ aqueous solution containing Ni and Fe at KHCO₃ :Fe:Ni=1:6:6 (molar ratio) gave a formic acid yield of 32.7% and an absorbent regeneration rate of 77.8%, indicating that the formic acid synthesis and chemical absorbent regeneration can be simultaneously achieved. However, it was also found that even under optimal conditions, the regeneration rate of the absorbent and the utilization rate of CO₂ cannot reach 100%. We will proceed with the design of the entire process, including the combination with CO₂ absorption and regeneration of the reductant, to evaluate its feasibility as a CCU process, as well as examine and propose the advantages of the proposed process over other CCU processes from an economic standpoint.