The response of a solid state microdosimeter based on semiconductor on insulator (SOI) technology to a 238PuBe neutron source was investigated. Simulations of the device response using the GEANT4 Monte Carlo Toolkit are also presented. The microdosimetric spectra was measured for lineal energies above 1 keV/nm. The possible application of the SOI microdosimeter for radiation protection applications in the form of a personnel microdosimeter is suggested. © 2005 IEEE.