Plasma source ion implantation (PSII) with high negative pulsed voltage applied to the workpiece is demonstrated as an effective low-temperature sterilization technique for three-dimensional work pieces. Using an N2 or Ar gas plasma and a pulsed voltage of -5 to -16 kV (10 μs pulse width, 900 pps), the method is shown to reduce the number of active Bacillus Pumilus spores by 3-5 log colony forming units after 15 min exposure.