In the paper, the formation of peroxide has been studied in the liquors and the model systems of ethanol aqueous solution under gamma irradiation. The G values of peroxide in irradiated liqour and ethanol systems have been gotten from the initial linear part of the curve. They are 1.0-3.6 for the different liquors and 3.6 for 60% ethanol aqueous solution respectively. It has been shown that oxygen plays an important role in the formation of peroxide. It has also been found that peroxide is rather stable in some liquors and its content remains higher up to 6-7 ppm after storage of 20 days. So, it is a urgent task to provide a H,2,O,2, safety limit in the irradiated liquors.