Recent research highlights the potential of molybdenum and tungsten sulfides as efficient hydrogen evolution catalysts (HER). These materials, including nanoparticulate MoS₂ and WS₂, the incomplete cubane-type [Mo₃S₄]⁴⁺ complex, and amorphous MoSₓ films, show promising catalytic activity for HER in aqueous solutions. The study summarizes their synthesis, structures, and catalytic properties, emphasizing their advantages over platinum-based catalysts in terms of cost, abundance, and scalability. Nanoparticulate MoS₂ and WS₂, synthesized via chemical vapor deposition and incipient wetness impregnation, exhibit high catalytic activity due to their edge sites, particularly the (1010) S edge. These edge sites are crucial for HER, as demonstrated by electrochemical measurements showing high exchange current densities and turnover frequencies. The catalytic activity of MoS₂ is further enhanced by doping with cobalt or nickel, which modifies the morphology and increases the proportion of active sites. The incomplete cubane-type [Mo₃S₄]⁴⁺ complex, a molecular MoSₓ compound, also shows significant HER activity. It is effective in catalyzing hydrogen evolution, although its activity decreases over time due to cluster desorption. Amorphous MoSₓ films, prepared by electropolymerization, exhibit high catalytic activity and stability, with a small Tafel slope, making them efficient for HER at reasonable overpotentials. In photocatalytic hydrogen evolution, MoS₂ and WS₂, when combined with photosensitizers like CdS or SiO₂, demonstrate high activity and stability under irradiation. These materials are particularly effective in solar-driven water splitting, offering a renewable and scalable alternative to platinum-based catalysts. Compared to other HER catalysts, MoS₂ and WS₂ materials offer significant advantages in terms of cost, abundance, and scalability. While their catalytic activity is comparable to platinum, their lower cost and ease of synthesis make them more attractive for practical applications. The understanding of the HER mechanism at the molecular level, particularly the role of sulfur ligands and edge sites, is crucial for the development of more efficient catalysts. In conclusion, molybdenum and tungsten sulfides are promising candidates for hydrogen production technologies due to their high catalytic activity, abundance, and cost-effectiveness. Their potential in photocatalytic and electrocatalytic applications highlights their importance in renewable energy systems. Further research is needed to optimize their performance and stability for large-scale applications.Recent research highlights the potential of molybdenum and tungsten sulfides as efficient hydrogen evolution catalysts (HER). These materials, including nanoparticulate MoS₂ and WS₂, the incomplete cubane-type [Mo₃S₄]⁴⁺ complex, and amorphous MoSₓ films, show promising catalytic activity for HER in aqueous solutions. The study summarizes their synthesis, structures, and catalytic properties, emphasizing their advantages over platinum-based catalysts in terms of cost, abundance, and scalability. Nanoparticulate MoS₂ and WS₂, synthesized via chemical vapor deposition and incipient wetness impregnation, exhibit high catalytic activity due to their edge sites, particularly the (1010) S edge. These edge sites are crucial for HER, as demonstrated by electrochemical measurements showing high exchange current densities and turnover frequencies. The catalytic activity of MoS₂ is further enhanced by doping with cobalt or nickel, which modifies the morphology and increases the proportion of active sites. The incomplete cubane-type [Mo₃S₄]⁴⁺ complex, a molecular MoSₓ compound, also shows significant HER activity. It is effective in catalyzing hydrogen evolution, although its activity decreases over time due to cluster desorption. Amorphous MoSₓ films, prepared by electropolymerization, exhibit high catalytic activity and stability, with a small Tafel slope, making them efficient for HER at reasonable overpotentials. In photocatalytic hydrogen evolution, MoS₂ and WS₂, when combined with photosensitizers like CdS or SiO₂, demonstrate high activity and stability under irradiation. These materials are particularly effective in solar-driven water splitting, offering a renewable and scalable alternative to platinum-based catalysts. Compared to other HER catalysts, MoS₂ and WS₂ materials offer significant advantages in terms of cost, abundance, and scalability. While their catalytic activity is comparable to platinum, their lower cost and ease of synthesis make them more attractive for practical applications. The understanding of the HER mechanism at the molecular level, particularly the role of sulfur ligands and edge sites, is crucial for the development of more efficient catalysts. In conclusion, molybdenum and tungsten sulfides are promising candidates for hydrogen production technologies due to their high catalytic activity, abundance, and cost-effectiveness. Their potential in photocatalytic and electrocatalytic applications highlights their importance in renewable energy systems. Further research is needed to optimize their performance and stability for large-scale applications.