Previous studies of thermal degradation of folic acid have not given consistent rate expressions or activation energies. The present study employed a model system which eliminated oxygen mass transfer limitations to examine degradation as a result of heating. A pseudo first-order reaction rate constant (k ah& and an activation energy (E,) for thermal degradation due to an oxidative mechanism were estimated to be 0.154 f 0.044 min-’ and 16.3 kcal/mol, respectively. In the presence of Nz, these parameters were estimated to be 0.094 ? 0.009 min-’ and 23.3 kcal/mol, respectively. While elimination of oxygen will not ensure folic acid retention, the overall degradation rate will be reduced significantly.