Stable and unstable isotopes of the heavy noble gas xenon find use in various medical applications. However, apart from 133Xe, used for Single Photon Emission Computed Tomography, radioactive isotopes of xenon are currently complicated to obtain in small quantities. With the GAMMA-MRI project in mind, we investigated a thermal sublimation generator of the long-lived excited state (isomer) 131mXe. This production method utilized the decay of 131I, obtained commercially from a hospital supplier in the form of Na131I powder. Heat treatments of the Na131I powder and cryogenic trapping of released 131mXe allowed us to collect up to 88% of the produced xenon. Our method provides an isomeric mixture of 131mXe and 131Xe. With improvements in scalability and chemical purification, this method could be a cost-effective source of 131mXe for small-scale experiments.