Recycled poly(ethylene terephthalate) (R-PET) was chain extended with pyromellitic dianhydride (PMDA) in an industrial scale twin-screw reactive extrusion system. Reactive extruded recycled poly(ethylene terephthalate) (RER-PET) samples at different PMDA concentrations were characterised in terms of rheological properties; thermal transitions and crystallinity. The results confirm the increase in molecular weight with an increase of PMDA concentration, and the formation of branching at concentrations above 0.25 wt.% PMDA. Structural changes due to PMDA addition affect the Tm, Tc and the crystallinity; however, no significant change was observed for the Tg.