In this paper we provide a review of the data processing required for successful discrimination of unexploded ordnance (UXO) with electromagnetic induction sensors. We present the time-domain dipole model commonly used for UXO discrimination and highlight some of the challenges encountered in real data sets from demonstration projects conducted by the Environmental Security Technology Certification Program (ESTCP). In particular, we show how magnetic soil response can be effectively modelled as an additional dipole source. We then compare sensor platform performance at a recent demonstration where small (e.g. 37 mm) ordnance were buried.