K2O and Na2O contents of a low-Be-Li cordierite coexisting with a granitic melt, characterised by a near constant Na/K ratio of 1.39 (in atomic proportions), have been determined as a function of P, T, aH2O and aCO2 in the range 3–7 kbar and 800–1000 °C. aH2O and aCO2 were calculated for individual experiments using measured H2O contents of cordierite and melt, and CO2 contents of cordierite. Na in the cordierite does not vary with P, T aH2O or aCO2 within this experimental range. The Na2O content is within analytical error of the value 0.120 wt% Na2O in all these experiments and thus does not support previous experimental results that showed more variable Na contents. K in cordierite increases (from 0.03 to 0.18 wt% K2O) with increasing T and decreasing aH2O (H2O content in cordierite and melt) but is not influenced by aCO2.