Abstract Silicon-on-insulator materials are being used in the development of radiation hard VLSI electronic circuits and one promising route is the use of porous silicon. Porous silicon is produced by electrochemically etching selected regions of silicon wafers to produce volumes of highly reactive porous silicon which can be converted to dielectric oxide or conducting metal or suicide. Results are presented of accelerator-based nuclear reaction measurements of the behaviour of porous silicon under a range of conditions. Oxidation behaviour as a function of temperature and different annealing conditions is reported together with evidence of the pick-up and removal of carbon. Fluorine, which has been reported to improve radiation hardness, has been implanted into porous silicon and is found to be very mobile at 1090 ° C. Preliminary results are also reported on the distribution of chemical vapour deposited tungsten in masked porous silicon structures.