Materials based on earth-abundant elements can be developed for hydrogen evolution reactions to meet the future demand for eco-friendly and renewable energy sources based on hydrogen. MoP nanoparticle assemblies in composite with reduced graphene oxide (rGO) have been introduced with superior electrocatalytic performances in hydrogen generation from both acidic and alkaline media. The composite drives HER with a current density ∼210 mA cm⁻² at a potential of 400 mV vs. RHE and requires only ∼80–90 mV to start hydrogen evolution in both media. This composite remains stable and durable for hydrogen evolution in an acidic medium after 20 hours of chrono-potentiometric studies at a current density of 100 mA cm⁻². Electrochemical hydrogen evolution studies show that an rGO based composite synthesized by an aniline complexation method exhibits higher catalytic efficiency than a composite synthesized by the citric acid complexation method. Detailed mechanistic investigations in both acidic and alkaline media have been carried out using impedance spectroscopy and the Tafel slope.