The effect of CO2 or steam partial pressure in the regeneration of CO2 solid sorbents was studied in the two-interconnected bubbling fluidized-beds system. Potassium-based dry solid sorbents, which consisted of 35 wt% K2CO3 for CO2 sorption and 65 wt% supporters for mechanical strength, were used. To investigate the CO2 capture efficiency of the regenerated sorbent after the saturated sorbent was regenerated according to the CO2 or steam partial pressure in the regeneration, the mole percentage of CO2 in the regeneration gas was varied from 0 to 50 vol% with N2 balance and that of steam was varied from 0 to 100 vol% with N2 balance, respectively. The CO2 capture efficiency for each experimental condition was investigated for one hour steady-state operation with continuous solid circulation between a carbonator and a regenerator. The CO2 capture efficiency decreased as the partial pressure of CO2 in the fluidization gas of the regenerator increased, while it increased as that of steam increased. When 100 vol% of steam was used as the fluidization gas of the regenerator, the CO2 capture efficiency reached up to 97% and the recovered CO2 concentration in the regenerator was around 95 vol%. Those results were verified during 10-hour continuous experiment.