The present paper investigates the availability of seawater as the absorbents to capture carbon dioxide (CO2) emitted from the coal fired power plant (CFPP). For the purpose of the study, readily obtainable alkali materials in CFPP such as coal fly ash (FA), NaOH and Ca(OH)2 are added to seawater to prepare the absorbents and their CO2 capture performances are discussed. FA can be effectively used the additives to increase CO2 capture capacity of seawater to a some extent. This is ascribed that some alkali components in FA are leached into seawater and they contribute to CO2 capture in the solution. However, their leaching amount and rate are restricted by the various ions in seawater. The performance of NaOH added seawater is even lower than that of NaOH added water because OH is substantially consumed on Mg(OH)2 production prior to carbonation. CO2 absorption capacity of Ca(OH)2 added seawater is slightly larger than that of Ca(OH)2 added water. This is because that Ca 2+ which originally present in raw seawater can participate in carbonation reaction.