The switching properties of a Programmable Metallization Cell (PMC) structure based on the Ag-As₂S₃ solid electrolyte were investigated. It was found that at 120 mV of forward bias voltage the device switches from an off state resistance to an on resistance state which is more than two orders of magnitude lower. To bring the structure back in an off state, a reverse bias of several volts is required. The frequency dependence of the switching threshold was carried out. Also is found that time required to switch the structure in a stabile on state is less than 10 μsec and around 60 μsec of reverse bias is required to put the structure back in an off state. The threshold voltage is shown to be nearly independent on temperature, but a linear increase of the on state resistance is observed within 20-80°C. The results are interpreted in terms of an electronic -superionic transition in chalcogenide glassy semiconductors due to a high concentration of dissolved metal.