The magnetic losses of steels used in high temperature superconducting (HTS) transformers are very important for the transformer’s efficient design and for a correct choice of operating conditions. This introduced the necessity to analyze electrical steels behaviour at low temperature in order to characterize their magnetic properties and, in particular, the magnetic losses. Three steels were chosen for this analysis: one non-oriented silicon steel and two different grain-oriented silicon steels. Several measurements of total magnetic losses were made at 77 K and 298 K and for different values of maximum magnetic induction, Bmax, in order to compare the dependence between them at both temperatures. These results are presented in . Subsequently, measurements of hysteresis losses (DC regime) at both temperatures were also made in order to obtain all terms of magnetic losses (hysteresis, classical eddy-current losses and excess losses). The results are presented in this paper.