The present investigation has been carried out to study the effect of -radiation on the absorption spectra of aerated solutions of alizarin complexone dye at different concentrations and pH values. The change in optical density for dosimeter concentrations ranging from 5·10–2 to 15·10–2 mM was observed to respond linearly to the increase of absorbed gamma dose. With the proper choice of concentration and pH value, the system is suitable for the accurate measurement of absorbed doses up to 5.3 kGy. This study includes also an investigation of the effect of environmental conditions on the stability of the dye solutions at different pH values during storage. Suggestions are made for possible low radiation dosimetry by means of spectrophotometric analysis of the absorption spectra.