The photochemistry course introduces students to the fundamentals of photochemistry, building on knowledge from physical and organic chemistry. It guides students from the processes of excited states of atoms and molecules, clarifying the principles of radiometry and sources of photochemically effective radiation. The course also covers the radiative processes involved in the decay of excited states and the reactivity of excited states, including the systematics of photochemical reactions of organic molecules. Finally, there is a strong emphasis on semiconductor photochemistry, conversion of solar radiation to other types of energy and semiconductor photocatalysis, and selected industrial applications. The course will provide students with background information beyond the basic study of photochemistry.