Diagenetic albitization of K-feldspar and plagioclase is a common diagenetic phenomenon in numerous sedimentary basins. Three geochemical codes (DISSOL, THERMAL, and KINDIS) are used to simulate these albitization reactions in terms of fluid chemistry and temperature. The geochemical codes show that albitization of K-feldspar is enhanced by increasing temperature, and is most likely to occur at 120-150 degrees C. Kinetic modeling of this reaction predicts the instability of quartz, which is generally considered a K-feldspar albitization product. Albitization of plagioclase is shown to decrease with increasing temperature. For low pCO 2 conditions it probably occurs between temperatures of 60 degrees C and 100 degrees C, while for higher values of pCO 2 it continues at temperatures greater than 100 degrees C.