<p>CO₂ sequestration into coal seams, coupled with enhanced coalbed methane recovery (CO₂-ECBM/sequestration), is increasingly recognized as a viable strategy for achieving global carbon neutrality objectives. This approach is particularly relevant in regions characterized by deep, unmineable coal seams or abandoned goafs resulting from the complete extraction of coal from mining fields. The adsorption of CO₂ on coal provides critical data necessary for CO2-ECBM/sequestration. This study systematically investigates the scientific challenges associated with quantifying CO₂ adsorption on coal using the manometric method under high-pressure conditions. It primarily addresses several key factors: the calculation of CO₂ density using the equation of state, the accuracy of temperature and pressure sensors, the implications of the CO₂ Joule-Thomson effect, phenomena related to coal adsorption swelling, and inconsistencies in temperature distribution within sample and reference cells. These issues can distort CO₂ adsorption measurements, rendering coal isotherms unreliable. Consequently, such factors may compromise both reproducibility and repeatability in supercritical CO₂ adsorption experiments conducted under high pressure, ultimately leading to distortions in the isotherms and negative adsorption profiles.</p>