天体化学（英语：Astrochemistry）；天体化学研究宇宙中元素和分子的丰度，以及它们和辐射的交互作用；还研究星际间气体和尘埃间的相互作用，特别是分子气体云的形成、相互作用和毁灭。天体化学和天文学以及化学有相互交叉之处。天体化学的研究范围包含了太阳系行星际物质和星际物质。而研究陨石等太阳系物质元素丰度和同位素比例的学科又被称为「宇宙化学」；研究星系物质中原子和分子以及前述物质和辐射交互作用的学科有时候称为「原分子天文物理学」。天文化学最主要研究星际分子云的形成、组成成分、演化和最终结局，因为这些相关知识与太阳系如何形成有关联。

Astrochemistry is the study of the abundance and reactions of chemical elements and molecules in the universe, and their interaction with radiation. The discipline is an overlap of astronomy and chemistry. The word "astrochemistry" may be applied to both the Solar System and the interstellar medium. The study of the abundance of elements and isotope ratios in Solar System objects, such as meteorites, is also called cosmochemistry, while the study of interstellar atoms and molecules and their interaction with radiation is sometimes called molecular astrophysics. The formation, atomic and chemical composition, evolution and fate of molecular gas clouds is of special interest, because it is from these clouds that solar systems form.