According to the data of the railway company JSC "Pasažieru vilciens" during the period from 2015 till 2021, the total number of unscheduled repairs for the broken bolts of the rubber-cord coupling was 180 cases, of which the largest part, according to statistical data, took place during the winter. To determine the causes of the M-24 bolts failure, studies were carried out to determine the chemical composition of the metal, as well as to determine the impact strength of bolts depending on temperature in accordance with EN ISO 898-1:2013 standard. The object of the study – bolts of rubber-cord coupling – was taken during the unscheduled repairs from ER2 series EMU trains motor cars No. 1341-08; No. 964-02 M-24. Dynamic tests, which are widely used in such cases, were carried out to identify the tendency of metals to brittle fracture. Dynamic impact tests were carried out on a Zwick/Roell RKP 450 machine according to ISO148-1:2017 standard at the independent KIWA «Inspecta» laboratory. In the article are reflected the determined chemical composition of the steel and the determined impact strength of the M-24 bolt samples of the rubber-cord coupling at three different temperature ranges. The article draws the main conclusions and offers recommendations for improving impact strength and specific impact strength at low temperatures.