The phase transformation induced resistive switching behavior of an Al/Cu2Se/Pt device was studied. While the device did not demonstrate any resistive switching behavior at room temperature, it exhibited resistive switching behavior at 125 degrees C, near the transition temperature of copper(I) selenide (Cu2Se) (137 degrees C), where Cu2Se is known to transform from the monoclinic to superionic phase. The increase in ionic conductivity and structural variations (from ordered to disordered structure) associated with phase transformation were observed to be responsible for the origin of the switching behavior and increase in the on/off resistance ratio near the transition temperature. Thermodynamic calculations showed that a reduction in Gibb's free energy of nucleation and an increase in the migration speed of the Cu ion associated with the ionic conductivity and order to disorder the transition of the Cu2Se at the transition temperature were the important factors responsible for the reduction in the SET voltages at 155 degrees C.