Global demand for hydrogen gas is expected to increase as efforts toward carbon neutrality intensify. Hydrogen emits no carbon dioxide during use and is regarded as a promising clean energy carrier, with technologies such as fuel cells being actively developed. However, most hydrogen is currently produced from fossil resources such as natural gas and oil, creating an urgent need for sustainable production methods. Although hydrogen can be produced from water or renewable feedstocks including alcohols, sewage sludge, and waste plastics, the high cost of these technologies remains a major barrier to practical implementation. Here we report a simple photocatalytic system for hydrogen production via alcohol dehydrogenation using iron, the most abundant and inexpensive metal on Earth. Driven by light energy, this ligand-free catalytic system represents a remarkably simple platform for sustainable hydrogen generation. The dehydrogenation of methanol using homogeneous or heterogeneous catalysts and photocatalysts has attracted considerable attention, as hydrogen production from alcohols represents a pivotal reaction for achieving carbon neutrality. Here, the authors report a photocatalytic system in which a ligand-free iron ion functions as the sole catalyst, promoting hydrogen evolution under UV light irradiation without the need for supporting ligands or noble metals, with similar turnover frequency compared to previously reported homogeneous catalysts.