Before the use of radiations to sterilize cefotaxime sodium powder, four new products radioinduced must be identified and qualified. They have an apparent level of or above 0.1%, at the sterilization dose of 25 kGy and are potentially toxic. Their identification is difficult because these products are formed at very low concentrations and generally have a structure similar as that of the main compound. The method proposed is to irradiate the drug in aqueous solution in order to increase the yields in radiolysis products, to compare the retention time of the new products, measured by high performance liquid chromatography, with those obtained after the irradiation of the solid drug and to identify from the aqueous solution the products which are common. One common product was found after the irradiation of cefotaxime in solid state and in aqueous solution. It was easily identified from the irradiated aqueous solution as anticefotaxime. This new product induced by the radiosterilization treatment, is not toxic but less active.