The amorphous/crystalline phase change behavior of Ag10Ge15Te75 (AGT) electrolyte was investigated. Satisfactory electrolytic resistive switching phenomena were observed in the memory cells composed of amorphous or crystalline AGT films sandwiched between Ag and Pt electrodes. The measured high and low resistance values of amorphous/crystalline cells are distinguishable and in different order of magnitudes. The electrically driven amorphous/crystalline phase change was also demonstrated in the cells sandwiched between two Pt electrodes. It is proposed that by controlling and using the electrolytic resistive switching in amorphous/crystalline cells and the electrically driven amorphous/crystalline phase change of these cells, a new type of four-state memory might be created. (C) 2010 The Electrochemical Society. [DOI: 10.1149/1.3523222] All rights reserved.