The reduction in size of field-effect transistors (FETs) comprised of 3D semiconductors is confronted with the issues such as short-channel effects, tunneling effects and thermal dissipation. The emergence of transition metal dichalcogenides (TMDCs) atomic layers has opened up unprecedented opportunities for scaling down of the electronics in view of their unique layered-structure and excellent properties. TMDCs grown directly on high-k dielectric substrates are beneficial for fabricating high-performance FETs. Here, we demonstrate the direct growth of atomically thin MoS2 flakes on high-kappa dielectric (HfO2) substrates via a chemical vapor deposition process. The morphology and structure of the as-grown materials were systemically investigated by optical microscope, atomic force microscope, Raman spectroscopy, photoluminescence, transmission electron microscope and X-ray photoelectron spectroscopy. The MoS2 flakes are approximately 5-10 A mu m in size with polycrystalline monolayer structure. The optical properties of the MoS2 flakes are also found to be substrate-dependent due to optical interference. In addition, back-gate FETs based on the as-grown MoS2 were fabricated and their performance was investigated. The results indicate that the n-type FETs show high on/off current ratio of 10(6) and a carrier mobility of 9.75 cm(2) V-1 s(-1).