In this study, an attempt was made to enhance the foamability and physical properties of ethylene-propylene diene (EPDM) rubber/ground tyre rubber (GTR) composite foams, thereby providing a potential new route to recycle discarded tyres. Pan-mill type mechanochemical reactor made in our lab was applied to realise the partial devulcanisation and ultrafine pulverisation of GTR. Fluorescence microscopy and scanning electron microscopy (SEM) studies indicated that the dispersion and interfacial adhesion between devulcanised GTR and ePDM matrix was much better than that of the untreated GTR and EPDM. The enhanced foamability through devulcanisation of GTR was confirmed by foaming rheological analysis. The physical properties of the composite foams were significantly improved through the devulcanisation of GTR. For the EPDM/GTR (100/30) composite foams, the rebound resistance was enhanced from 37;to 51;while the compression set was decreased from 43;to 33;via the devulcanisation of GTR. It has been proved that the mechanochemically devulcanised GTR can be used as a low cost but effective functional additive for enhancing the rebound resistance properties of EPDM foams.