In this paper dynamic properties of HTK 700H, HTK 900H, Hardox 400 and Hardox 500 steels in delivered State (after hardening and tempering) are considered. Charpy V - notch (CVN) test results in connection with fractography in the ductile - to - brittle transition temperature region were analyzed. The impact transition curve obtained from CVN test not always predicts properly a behavior of materials in conditions of dynamic loading, so the analyze of character of fracture helps to evaluate the real behavior of materials. Tested samples were cut out longitudinally and transversely in relation to cold work direction. The results of CVN test for investigated steels, in the range of temperatures from -40 to 20 °C are presented. Regarding ductile - to - brittle transition temperature, there is a significant difference taking into account values of Charpy V energy absorbed and a character of fracture.