Abstract: The melting points of eight known compounds have been determined by DTA at the temperature ranging from 50℃ to-150℃. The results are accurate to ±1℃. The melting points of dioxane and cyclohexane,as reported in the literature, are 11℃ and 6.5℃, but another ones have been found by this method at 1℃ and-86℃,respective-ly. It is considered to be related to the conformations of the two compounds. Phase diagrams for two component system have also been obtained using low temperature DTA technique.