Carbon dioxide (CO2) capture and storage (CCS) technology has emerged and become a promising tool for the control of greenhouse gas emissions. CCS is applicable to the integrated coal gasification combined cycle (IGCC) equipped with a water-gas shift reaction (IGCC-CCS). In our previous studies, we obtained novel chemical absorbents suitable for IGCC-CCS and examined vapor-liquid equilibria of the absorbents. However, the mechanisms of dissolution of pressurized CO2 into the solvents (e.g., determination of the fractions of CO2 absorbed chemically and physically under high CO2 pressure conditions) were not clear, even though this information is very important For estimation of the energy requirements For the CCS process. We examined the usefulness of C-13 NMR spectroscopy to determine CO2 solubility and the components of inorganic carbon species (bicarbonate/carbonate and molecular CO2) in six different amine-containing aqueous solvents, at temperatures ranging from 40 to 70 degrees C and CO2 pressures ranging from 0.5 to 4 MPa. We found that (i) the amounts of CO2 physically absorbed into the solvents increased with increasing CO2 pressure and comprised 15-30% of the total CO2 in all the solvents at 40 degrees C and 4 MPa, and (ii) the Solubility determined by C-13 NMR spectroscopic and vapor-liquid equilibrium measurements were in good agreement over the CO2, pressure range examined. The results indicate that we could not only obtain CO2 solubility data but also identify the inorganic carbon species in the solvents by quantitative C-13 NMR spectroscopy.