The thermal analysis is very effective tool in the study of thermophysical and thermodynamical properties (e.g. temperatures of phase transformations, latent heats -enthalpies of phase transformations,...) among others, metallic systems. One of the most widespread methods of thermal analysis used for the description of metallic systems behaviour is the Differential Thermal Analysis - DTA. The aim of our work was study of characteristic phase transformation temperatures (temperatures of solidus - T$ and liquidus - TL) of lead-free solders on the base of tin. In total 22 alloys with different ratios of individual elements Ag, Cu, In, Sb, Bi, Zn and Sn were prepared experimentally. In addition, six alloys of lead-free solders produced commercially (Kovohute Pf ibram) were used and the Pb-Sn solder served as a comparative alloy. The alloys were prepared by smelting of input metals in the graphite crucible followed by casting into graphite boat. Temperatures of solidus and liquidus were obtained with use of experimental laboratory system SET ARAM SETSYS 18TM TG/DTA/TMA. Samples of solders in the form of small disordered pieces (size up to approx. 3 mm and max. mass 0.2 g) were during measurement heated and cooled in a controlled manner at the rate of 4°C/min. The A12O3 crucibles were used for measurement. Argon (purity > 99.999999%) was used for washing of the inert space of oven before each analysis (flow time approx. 15 min), then evacuation followed and again filling up with argon. During analysis the constant dynamical atmosphere was kept in the oven space (flow rate of argon was 2 1/h). Differences between experimentally determined temperatures of Ts, TL acquired during controlled heating and cooling were observed. These differences could be influenced not only by undercooling, but also by dynamics of measuring process.