This paper present a study carried out in the frame of a collaborative research project carried out between California Polytechnic State University (Cal Poly) and Politecnico di Torino (PoliTO) regarding the development of an innovative, simple, low cost, regenerative cooling system for a convergent-divergent nozzle of a N2O-PMMA hybrid rocket engine. Regenerative rocket nozzle cooling technology is a well-developed technology for liquid rocket engines (LREs), but it has yet to be widely applied to hybrid rockets. Due to the high heat fluxes that a rocket experiences in its nozzle throat, most nozzles are predisposed to ablation, supporting the need to implement a cooling system.