Soil freezing characteristic curve (SFCC) represents the relationship between soil temperature and unfrozen water content of soil during freezing and thawing processes. In this study, SFCC of sandy soils was determined in laboratory. Pure sand was mixed with clay at various contents (0, 5, 10, 15, and 20% of the total dry mass) and the mixtures were compacted to their respective maximum dry density. Compacted specimens were then placed in a close and rigid cell and the soil's temperature was decreased step-by-step to freeze the soil water and then increased back to thaw it. During this thermal cycle, soil's temperature and volumetric water content were monitored in order to determine the SFCC. The results show that SFCC was strongly dependent on the fines content: at higher fines content, the temperature of spontaneous nucleation was lower and the residual unfrozen volumetric water content was higher.