The resistive switching characteristics of the Cu/SiO x /Pt structure (control sample) exhibited a direct correlation to humidity. The H2O vapor formed the Cu oxide at the Cu/SiO x interface, and Cu ions were injected from the Cu oxide into the SiO x layer, thus improving the resistive switching. However, the control sample demonstrated substantial switching dispersion in a vaporless environment. The Cu x O layer in the Cu/Cu x O/SiO x /Pt structure (Cu x O sample) helped the dissolution of Cu ions from the Cu electrode into the SiO x layer, enabling effective electrochemical resistive switching in a vaporless environment. The Cu x O sample exhibited low switching dispersion and favorable endurance characteristics in a vaporless environment.