The article reviews recent advancements in the use of molybdenum and tungsten sulfide materials as catalysts for hydrogen evolution (HER) in aqueous solutions. These materials, including nanoparticulate MoS₂ and WS₂, incomplete cubane-type [Mo₃S₄]⁴⁺ complexes, and amorphous MoSₓ films, show promise for clean hydrogen production technologies due to their low cost and abundance. The synthesis methods, structural characteristics, and catalytic activities of these materials are discussed. Key findings include: 1. **Nanoparticulate MoS₂ and WS₂**: These materials exhibit high HER activity, with exchange current densities ranging from 1.3 × 10⁻⁷ to 3.1 × 10⁻⁷ A cm⁻² geometric. The edge sites of MoS₂ nanoparticles are identified as the catalytically active sites. 2. **Incomplete Cubane-Type [Mo₃S₄]⁴⁺**: This molecular complex, containing undercoordinated sulfur, shows HER activity similar to that of nanoparticulate MoS₂, with a turnover frequency (TOF) of 0.07 s⁻¹. 3. **MoS₂ in Photocatalytic Hydrogen Evolution**: MoS₂ can be used as a catalyst in photocatalytic hydrogen production, showing activity under visible light irradiation. The optimal loading of MoS₂ on CdS is about 0.2 wt%. 4. **Amorphous MoSₓ Films**: These films, prepared by cyclic voltammetry, exhibit high HER activity with exchange current densities between 1.5 × 10⁻⁷ and 0.4 × 10⁻⁷ A cm⁻² geometric. They are stable against CO, CO₂, and O₂, suggesting that sulfur ligands play a crucial role in catalysis. 5. **Comparison of Catalysts**: The amorphous MoSₓ films show the highest geometric current density at a given overpotential, making them a promising candidate for practical applications due to their high activity, cost-effectiveness, and scalability. The article concludes that molybdenum and tungsten sulfide materials are promising for hydrogen production technologies, with ongoing research focusing on understanding the HER mechanism at the molecular level and developing more efficient catalysts.The article reviews recent advancements in the use of molybdenum and tungsten sulfide materials as catalysts for hydrogen evolution (HER) in aqueous solutions. These materials, including nanoparticulate MoS₂ and WS₂, incomplete cubane-type [Mo₃S₄]⁴⁺ complexes, and amorphous MoSₓ films, show promise for clean hydrogen production technologies due to their low cost and abundance. The synthesis methods, structural characteristics, and catalytic activities of these materials are discussed. Key findings include: 1. **Nanoparticulate MoS₂ and WS₂**: These materials exhibit high HER activity, with exchange current densities ranging from 1.3 × 10⁻⁷ to 3.1 × 10⁻⁷ A cm⁻² geometric. The edge sites of MoS₂ nanoparticles are identified as the catalytically active sites. 2. **Incomplete Cubane-Type [Mo₃S₄]⁴⁺**: This molecular complex, containing undercoordinated sulfur, shows HER activity similar to that of nanoparticulate MoS₂, with a turnover frequency (TOF) of 0.07 s⁻¹. 3. **MoS₂ in Photocatalytic Hydrogen Evolution**: MoS₂ can be used as a catalyst in photocatalytic hydrogen production, showing activity under visible light irradiation. The optimal loading of MoS₂ on CdS is about 0.2 wt%. 4. **Amorphous MoSₓ Films**: These films, prepared by cyclic voltammetry, exhibit high HER activity with exchange current densities between 1.5 × 10⁻⁷ and 0.4 × 10⁻⁷ A cm⁻² geometric. They are stable against CO, CO₂, and O₂, suggesting that sulfur ligands play a crucial role in catalysis. 5. **Comparison of Catalysts**: The amorphous MoSₓ films show the highest geometric current density at a given overpotential, making them a promising candidate for practical applications due to their high activity, cost-effectiveness, and scalability. The article concludes that molybdenum and tungsten sulfide materials are promising for hydrogen production technologies, with ongoing research focusing on understanding the HER mechanism at the molecular level and developing more efficient catalysts.