The aim of this thesis was to develop and process viable rubber-thermoplastics blends from ground tyre rubber (GTR) and waste polypropylene (WPP). The use of WPP with waste rubber in blends is novel, although limited studies have been carried out on virgin polypropylene (PP)-waste rubber blends. The Delink pretreatment for the GTR is also a novel technique used for property enhancement. To achieve the aim, a number of GTR/WPP blends were prepared, in different blend compositions (from 0 to 100 wt% of each polymer), at different processing parameters, and with two compatibilizing systems. One system called dimaleimide contained N-N' meta-phenylene dimaleimide (HVA-2) as the compatibilizer and either di(tert-butylperoxyisopropyl) benzene (DTBPIB) or 2-2'-dithiobenzothiazole (MBTS) as an activator. The other system contained phenolic resin compatibilizer (SP 1045H resin) and stannous chloride (SnCl2) activator in two forms: anhydrous and dihydrated. The compatibilizer level varied from 0 to 5 pphp, while the activator level varied from 0 to 1 pphp.