The article is dedicated to the problem of increase of viability of triticale and maize seeds under the conditions of their ex situ conservation with the help of millimeter radiation (MMR). The effect of low temperature (LT) upon the seeds was also studied separately and in combination with MMR. Various parameters of seeds and seedlings were determined: physiological (germinating power and germinability of seeds, bioisomerism of seedlings). It was revealed that influence of millimeter radiation with the wavelength of 5.6 mm, power density 6.6 mW/cm2 and exposures of 2, 8 and 30 min on dry seeds of triticale and maize results in the highest stimulation of germination processes. In the joint processing of seeds by MMR and LT there have been detected both protective and reparative effects. Selected irradiation mode of triticale and maize seeds with MMR after their long-term storage in plant gene bank contributed to the increase of seed viability. It was manifested in the increase of germinating power and germinability of seeds, but also in maximal growth of seedlings.