An apparatus for generating a flow of reactive gas for decontaminating a material, surface or area, which comprises a first electrode member comprising a first conductive sheet and a first plurality of conductive pins protruding from a surface of the first conductive sheet and a second electrode member comprising a second conductive sheet and a second plurality of conductive pins protruding from a surface of the second conductive sheet. The second electrode member is arranged in spaced relationship with the first electrode member to define a reactor channel between the first conductive sheet and the second conductive sheet The first plurality of conductive pins protrude within the reactor channel towards the second conductive sheet and the second plurality of conductive pins protrude within the reactor channel towards the first conductive sheet so as to form air gaps between the first plurality of conductive pins and the second plurality of conductive pins. An air blower generates a flow of air through the reactor channel. An electric pulse generator repetitively generates voltage pulses between the first and second electrode members so as to produce glow discharges in the air gaps between the conductive pins of the first plurality and the conductive pins of the second plurality, the voltage pulses being generated at a pulse repetition frequency greater than about 1 kHz and voltage pulse duration less than about 100 ns, the glow discharges being adapted to transform part of the flow of air into reactive gas. An output section delivers the reactive gas from the reactor channel to a sample or region to be decontaminated.