Problem statement: The electrical properties of thin film structures consisting of metalinsulator-metal sandwiches are important in electronic devices. Approach: The electrical properties of thin film structures consisting of metal-insulator-metal sandwiches are investigated in this experimental work. Results: We are discussed of the electroformed metal-insulator-metal structures Au-MgF 2-Au and comparison with other Au-SiO/CeF 3-Au, Cu-CeF 3-Cu, Cu-SiO-Cu, Au-CeF 3-Au specimens. There explains various properties including electron emission, electroluminescence, memory effects and, the differential negative resistance. The article is based upon experiments which identify the conduction process to be trap-controlled thermally activated tunneling between metal islands produced in the forming process. These devices undergo an electroforming process leading to resistivity decrease of several orders of magnitude along with a negative resistance region in their I-V characteristics. Conclusion/Recommendations: Experimental results show that Cu-SiO-Cu and Au-MgF 2-Au Mg specimens have high circulating current at room temperature and can be implication for the production of commercial electroformed devices such as cold cathode.