AbstractAqueous solution of pH indicator dye tetrabromophenolphthalein ethyl ester containing chloral hydrate was studied for its possibility to be used as a liquid dosimeter. The useful measuring range was found to be (0.5–2 kGy) depending on the concentration of both dye and chloral hydrate added. The system has good stability before and after irradiation under different storage conditions. A comparison study between direct irradiation of the dye containing chloral hydrate and indirect method that executed through avoiding exposure of the dye to irradiation and irradiate the chloral hydrate only followed by outputs for interaction with dye was investigated seeking to extend the dose range up to 5 kGy.