We have recently synthesised the novel iridocuprate IrSr2Sm1.15Ce0.85Cu2O10. This material exhibits a complex temperature dependence of the magnetic susceptibility with multiple magnetic transitions characteristic of re-entrant spin-glass behaviour. In a re-entrant spin-glass these consecutive transitions upon cooling can be assigned to: t1, the initial formation of ferromagnetic clusters that grow in size upon cooling; t2, the onset of a disordered spin component; and t3, a second spin-glass disordering transition. Mixed oxidation of the Ir4+/5+ ion, and as such magnetic-disorder (j=1/2 and j=0 respectively), is the likely cause of the glassy behaviour. We propose to measure the spin dynamics of this complex magnetic material on the MUSR spectrometer between 1.5 K and 400 K. This will also allow us to calculate the volume fraction of the spin clusters.