The enthalpies of the crystal transformation from I to II and from II to III and the melting enthalpy of 2,2,2-trinitroethyl-4,4,4-trinitrobutyrate (TNETB) are determined by means of Calvet microcalorimeter. On cooling, the supercooing from liquid to solid does not appear, and form II will transform to form I when 71.8° C is reached. The phase diagrams of TNETB-2,4,6-trinitrotoluene (TNT) and TNETB-polyester systems have been constructed by differential scanning calorimetry (DSC). The eutectic temperatures are 56° C and 34° C respectively. The compositions corresponding to the eutectic points are 52 and 46 weight percent TNETB respectively.