The stoichiometric compound Cu2PbO2 has been synthesized by solid-state reaction from Cu2O and PbO in a sealed quartz ampoule. The optimum synthesis conditions are 9 10 K and 260 h. The enthalpy of formation of Cu2PbO2 has been measured with the use of high-temperature calorimeter. The enthalpy of reaction Cu2O + PbO = Cu2PbO2 is -25.4 +/- kJ(.)mol(-1) at temperature 968 5 K. Standard enthalpy and Gibbs energy of formation of the Cu2PbO2 compound from elements and its entropy at 298.15 K are Delta(f)H degrees = -413.086 kJ(.)mol-1, Delta(f)G degrees = -353.165 kJ(.)mol(-1) and S degrees = 135.165 J(.)mol(-1.)K(-1). The eutectic reaction L -> Cu2O + PbO was found to occur at 1017 +/- 5 K. Using the thermodynamic database for Cu-Pb-O system the revised Cu2O-PbO phase diagram is proposed.