A footwear sanitizing device is insertable into footwear to be sanitized. The device includes a self-contained ion generator that subjects the footwear to an outflow of ionized air containing safe amounts of ozone. The ion generator includes a high voltage generator whose output pulses are coupled between first and second electrode arrays disposed in a pair of electrode assemblies. Preferably each first array comprises at least one metal pin spaced coaxially-apart from a metal ring-like structure. Alternatively, the first array may comprise at least one wire electrodes spaced staggeringly apart from a second array comprising hollow "U"-shaped electrodes. Preferably a ratio between effective area of an electrode in the second array compared to effective area of an electrode in the first array exceeds about 15:1 and preferably is about 20:1. An electric field produced by the high voltage between the arrays produces an electrostatic flow of ionized air containing safe amounts of ozone. The outflow of ionized air and ozone is directed toward the footwear being sanitizer.