The amount of first stage coloration in NaCl doped with Ca2+, Sr2+Cd2+, or Eu2+has been investigated as a function of the X-irradiation dose rate. It was ascertained that in all cases the amount of first stage coloration is proportional to the square root of X-irradiation dose rate in agreement with the models recently developed by Comins and Carragher and Aguilar et al for F-center produc tion in the alkali halides doped with divalent impurities.