This article presents a novel electrocatalyst for hydrogen generation based on atomic cobalt dispersed on nitrogen-doped graphene (Co-NG). The catalyst is highly active and robust, with a very low overpotential (30 mV) in aqueous media. The catalytic activity is attributed to the metal centers coordinated to nitrogen atoms. The Co-NG catalyst is synthesized by heat-treating graphene oxide and cobalt salts in an ammonia atmosphere. The resulting catalyst has a high surface area, good stability, and excellent electrical conductivity, making it suitable for electrocatalytic applications. The Co-NG catalyst is highly efficient in both acidic and basic conditions, outperforming other catalysts such as MoS₂, WS₂, CoP, and MoP. It also shows superior stability, with minimal degradation after 10 hours of continuous operation. The catalyst is scalable and cost-effective, making it a promising alternative to platinum for water splitting applications. The study highlights the potential of single-atom catalysis in creating highly efficient and sustainable electrocatalysts for hydrogen generation.This article presents a novel electrocatalyst for hydrogen generation based on atomic cobalt dispersed on nitrogen-doped graphene (Co-NG). The catalyst is highly active and robust, with a very low overpotential (30 mV) in aqueous media. The catalytic activity is attributed to the metal centers coordinated to nitrogen atoms. The Co-NG catalyst is synthesized by heat-treating graphene oxide and cobalt salts in an ammonia atmosphere. The resulting catalyst has a high surface area, good stability, and excellent electrical conductivity, making it suitable for electrocatalytic applications. The Co-NG catalyst is highly efficient in both acidic and basic conditions, outperforming other catalysts such as MoS₂, WS₂, CoP, and MoP. It also shows superior stability, with minimal degradation after 10 hours of continuous operation. The catalyst is scalable and cost-effective, making it a promising alternative to platinum for water splitting applications. The study highlights the potential of single-atom catalysis in creating highly efficient and sustainable electrocatalysts for hydrogen generation.