A recently measured value of the dipole moment of H2SO4 necessitates a recalculation of stratospheric negative ion reaction rate constants with H2SO4. The measured reaction rate constants were normalized to a theoretical limit which depends on this dipole moment. The revised values are increased by the factor 2.7. Deduced values of stratospheric vapor phase sulfuric acid from ion composition measurements are inversely proportional to the reaction rate constants.