The solubility of CO2 in the molten Na2CO3-K2CO3 eutectic mixture at 800 degrees C has been measured using a manometric method. The corresponding Henry’s constant amounts to 1.83 10(-1) moll(-1) atm(-1) which is a rather high value in comparison with other values reported in the literature for CO2 in carbonate melts at lower temperature. A diffusion coefficient of 4.5 x 10(-5) cm(2) s(-1) has been evaluated from the experimental data for CO2 in the investigated melt. The CO2/CO system is electroactive but the peak current for the reduction of CO2 appears to be low if the solubility is taken into account. An explanation is proposed which involves the production of C2O52- ions by reaction between CO2 and the melt.