The development of electrocatalysts based on metal NPs and semiconductors for the hydrogen evolution reaction (HER) and oxygen reduction reaction (ORR) holds significant promise to a spectrum of energy conversion technologies. MoS2 is a promising candidate for electrochemical hydrogen production due to its high activity and stability. However, the efficiency of hydrogen production by MoS2 is limited by the number of active sites, e.g. edges, which can be improved by changing the morphology or combining MoS2 with other materials to get the surface more catalytically active. Here we show the preparation, characterization and catalytic activity towards HER and ORR of Cu@MoS2 hybrid nanostructure. Understanding the dual effect of the metal NPs over MoS2 can shed light over the catalytic mechanism of this system and can have a rich platform for designing a new well improved based-semiconductor-metal NPs catalyst for energy related application. We show the nature of the bonding of metal NPs and MoS2. TEM images of Cu@MoS2 present nanostructured metal NPs (30 nm in average) wrapped with multi-layers of MoS2. The formation of crystalline MoS2 around the metal NPs is proved by XPS and XRD analysis. High-resolution transmission electron microscopy of the hybrid provides direct evidence of the core–shell morphology. The initial attachment of MoS42- to Cu NPs during the synthesis and after the thermal treatment, is also analyzed by XPS. Electrochemical measurements show that the hybrids’ catalytic activity is better than the sole MoS2 or Cu NPs. The core is more than a mere support for the shell, and complex interfacial interactions (electronic and mechanical) can affect the properties of few-layer shells. The large enhancement in the catalytic activity can be attributed to the synergistic effect of charge transfer to the MoS2 and a morphological effect in which more active sites are exposed due to the curvature of MoS2 around the NPs.