This work is devoted to the study of the effect of overheating of metal melts on their supercooling before crystallization. Melting and crystallization are important technological processes for producing high-quality castings. The direct study of the processes involved in casting metals and their alloys is extremely difficult because they are opaque, take place at very high temperatures and sometimes occur in aggressive environments. In this regard, we have applied the physical modelling method to conduct these studies, using the low-temperature metal alloys Wood and Rose and the organic media diphenylamine and camphene as objects of study. To conduct the research, a special experimental setup was created and a physical modelling technique is developed. In the experiments, three prototypes of equal weight were prepared from each model alloy on an electronic balance with a weighing accuracy of 0.01 g. To ensure the absolute identity of the melting and crystallization conditions of the model alloys, all three test samples were simultaneously placed in a thermostatically controlled chamber. The samples are gradually heated to melt and superheat to a certain level. After the melt is held in the superheated state, it is cooled to the temperature of nucleation, which is recorded using thermocouples. The signal from the thermocouples is observed on the screen of the potentiometer in the form of absolute digital temperature values, and on the laptop screen in the form of temperature curves of cooling of the melts of the test media. The magnitude of melt supercooling, at which crystals nucleate, is determined by characteristic features on the cooling temperature curve of the model medium, i.e., the appearance of boards on them due to the release of crystallization heat. In experiments on transparent organic media (camphene and diphenylamine), the accuracy of fixing the amount of supercooling in their melts using thermocouples is also controlled visually by observing the moment of crystal nucleation in them. As a result of the research, it is found that the effect of overheating on supercooling of the studied alloys is most likely due to a change in the concentration of limitedly soluble impurities. This assumption is based on the fact that the dissolution of impurities in the melt of any metal occurs as a result of diffusion, which is a relatively time-consuming process, and to obtain greater homogeneity of the metal melt, it is necessary either to increase the temperature of its overheating or to ensure its longer holding in the overheated state. The results of our research confirmed these assumptions. With an increase in the degree of dissolution of impurities, the supercooling of model melts changes, which is due to a change in the physical and chemical properties during the nucleation of crystals.