The effects of methylparaben, frequently used preservative, on the gelatinization and solid state decomposition of corn starch were determined. It was observed that methylparaben causes a decrease in the gelatinization temperature of the starch by up to 14.8 degrees C. The starch was shown to degrade in two consecutive reactions, an initial dehydration, followed by the formation of a carbonaceous residue. The decomposition was altered by the methylparaben, as suggested by an increase in the temperature of the dehydration reaction, indicating that a higher temperature was required to drive off the bound water. The activation energy for the major decomposition was also higher when the preservative was present. The methylparaben was shown to evaporate via a zero-order kinetic process, with an increasing activation energy in the presence of corn starch. The melting point was unaffected.