For the first time, to the best of our knowledge, the electron-hole pairs generated in a material by a single photon ionization event have been detected using a microwave technique. The detection mechanism is based on the attenuation of a resonant electromagnetic wave and, unlike conventional particle detectors, does not rely on charge or scintillation light collection. The current technique has an inherent fast response (microwave frequency of 9 GHz) and is not affected by the problems associated with charge sweeping and/or light measurements. Experimental results for single high energy x-ray photons absorbed in high purityp-germanium are presented. The results demonstrate the potential for a new class of gamma/particle detectors and a useful method to study the kinetics of particle interactions in materials. ©1997 American Institute of Physics.