Spray cooling heat transfer was studied experimentally using deionized water to investigate spray cooling of a smooth surface and nano- and hybrid micro/nano-structured surfaces. The nano-structures were ZnO nanowires grown on silicon substrates using the wet chemical method while the hybrid micro/nano-structures were obtained by depositing carbon nanotube (CNT) films on micro structured silicon surfaces fabricated through electrochemical deep reactive ion etching (DRIE). The results show that the heat transfer is enhanced on the nanostructured surfaces compared to the smooth surface. Coating CNT films on the micro-structured surfaces to form hybrid structures further improves the spray cooling heat transfer on the micro-structured surfaces.