Proton reduction is one of the most fundamental and important reactions in nature. MoS2 edges have been identified as the active sites for hydrogen evolution reaction (HER) electrocatalysis. Designing molecular mimics of MoS2 edge sites is an attractive strategy to understand the underlying catalytic mechanism of different edge sites and improve their activities. Herein I will discuss our recent progress in this aspect. The first example is a dimeric molecular analog [Mo2S12]2-, as the smallest unit possessing both the terminal and bridging disulfide ligands. Our electrochemical tests show that [Mo2S12]2- is a superior heterogeneous HER catalyst under acidic conditions. Computations suggest that the bridging disulfide ligand of [Mo2S12]2- exhibits a hydrogen adsorption free energy near zero (-0.05 eV). The second example is a group of compounds with the general formular of MoO(S2)2bpy. By varying substitution on the bpy ligand, we demonstrate the induction effect on the S—S ligand, thereby tuning the rate constants for HER and overpotentials. We have studied homogenous electrocatalytic hydrogen production performance metrics of three catalysts with different bipyridine substitutions. By varying the electron-donating abilities, we present the first demonstration of using the ligand to tune catalytic properties of the S—S bond in molecular MoS2 edge site mimics. These works can shed light on the relationship between structure and electrocatalytic activity of molecular MoS2 catalysts and thus is of broad importance from catalytic hydrogen production to biological enzyme functions. Lastly, I will discuss how to integrate the molecular catalysts into dye-sensitized photoeletrochemical platforms for solar hydrogen production.