Efficient electrocatalysts for hydrogen evolution reaction (HER) in alkaline solution are highly required for water splitting.Here we design an ultra-small PtOx nanopatticle with hybrid Pt chemical states on carbon nanotubes as highly efficient alkaline HER catalyst,which shows a low overpotential of 19.4 mV at 10 mA cm-2,a high mass activity of 5.56 A mg-1Pt at 0.1 V,and a stable durability for at least 20 h.The HER performance is better than that of the benchmark 20 wt％ Pt/C while the Pt content in the catalyst is only about one tenth of that in Pt/C.It also represents one of the best catalysts ever reported for HER in alkaline solution.Synchrotron radiation X-ray absorption spectroscopy reveals that the efficient and stable alkaline HER performance can be attributed to the favorable design of hybrid chemical states of Pt with carbon nanotubes,which exhibits abundant surface Pt-O as active catalytic sites and forms stable Pt-C interfacial interaction to both anchor the NPs and improve the synergistic effect between catalyst and substrate.