Driven by population and quality of living increases, the global consumption of energy is expected to dramatically increase over the course of the century. To avoid meeting this demand with fossil fuels, new carbon neutral energy sources must be implemented which are competitive in cost and performance with those currently in use. Hydrogen is a possible candidate to meet this need but carbon-free production of hydrogen needs to be developed. This chapter specifically examines the progress of homogeneous catalysts used in hydrogen production via artificial photosynthesis. Only those catalysts based on earth abundant metals, such as Co, Ni, Fe, and Mo are discussed as inexpensive mass production would require such materials, as opposed to expensive and rare metals, such as Pt, Pd and Rh. Electrocatalytic studies are also discussed as it pertains to the light driven systems and mechanistic insights.