The effect of γ-radiation on the extraction properties of two functionalized calixarenes (p-tert-butyl-thiacalix[4]arene and p-tert-butylcalix[8]arene) is studied. The most characteristic products of the irradiated extractants interaction with diluent are identified by mass spectrometry. Extraction ability of studied calixarenes towards cesium and americium before and after irradiation is evaluated. Quantitative analysis of chloride and sulfate ions after irradiation is performed to estimate the radiological degradation degree of components. Irradiation has different effect on p-tert-butyl-thiacalix[4]arene and p-tert-butylcalix[8]arene extraction ability towards americium, which may be due to the nature and extraction ability of radiolysis products, and practically does not affect cesium extraction.