The fabrication of memory devices based on the Ag/PMMA:Na/Ag structure and their electrical characteristics are reported. The Ag/PMMA:Na/Ag devices show a hysteresis behavior with different Na contents. The most evident hysteresis behavior for memory effect, represented as the on/off current ratio, is found to be as high as 105 in Ag/PMMA:Na-180 s/Ag devices. The carrier conduction mechanisms between the high and low resistance states and the transition states are further examined on the basis of trap-assisted space charge limited current theory. Such devices sustain at least 60 operation iterations and 100 s duration tests. Hence, the idea of incorporating Na particles into the organic layer of memory devices creates a promising direction for the development of organic memory devices. (C) 2016 Elsevier B.V. All rights reserved.