Choline chloride (ChCl) is a well-known material forming deep eutectic solvents (DESs) when mixed with a hydrogen bonding donor (HBD). The potential applicability of DES systems is wide for replacing ionic liquids at relatively low cost. Therefore, the application to chemical processes necessitates the reliable data of DES properties. In this work, thermal behaviors of two ChCl-based DES systems (ChCl + urea and ChCl + 1,3-dimethylurea) were investigated by using a differential scanning calorimeter. Crystalline as well as amorphous characteristics were found by varying compositions. In general, the increased composition of ChCl strengthened the crystallinity of solid phase. In the ChCl + urea system, a phase diagram was drawn with obtained melting point data while it could not be available for the other system.