A micro-scale thermosyphon heat pipe technology which passively utilizes 3D chip's specific micro channels structure as the evaporating section of the thermosyphon to form a thermosyphon boiling in micro-channels for 3D chip cooling is proposed. The maximum heat flux and heat transfer coefficient of thermosyphon boiling in micro -channels which simulated actual 3D chip structure were experimentally studied. Experiments were carried out using four kind of working liquids: two pure fluids (deionized water and R113), super -moist fluids (R113 + surfactant) and nanofluids (R113 + surfactant + CuO nanoparticles). The height and gap of channels used were in the range of 30 mm to 100 mm and 30 Am to 1 mm, respectively. Experimental results show that nanofluids can significantly enhance both the maximum heat flux and heat transfer coefficient of thermosyphon boiling in micro -channels due to super-wettability of the liquid and the formation of a porous sedimentary layer consisted of nanopartides on the wall. The results show that the micro thermosyphon heat pipe structure is a promising technology for 3D chip cooling. (C) 2016 Elsevier Ltd. All rights reserved.