Chemical engineering is the branch of engineering that deals with the application of physical science (in particular chemistry and physics) and mathematics to the process of converting raw materials or chemicals into more useful or valuable forms. As well as producing useful materials, chemical engineering is also concerned with pioneering valuable new materials and techniques; an important form of research and development.

Chemical engineering largely involves the design and maintenance of chemical processes for large-scale manufacture. Chemical engineers in this branch are usually employed under the title of process engineer. is a professional who works principally in the chemical industry to convert basic raw materials into a variety of products, and deals with the design and operation of plants and equipment to perform such work In general, a chemical engineer is one who applies and uses principles of chemical engineering in any of its various practical applications; these often include 1) design, manufacture, and operation of plants and machinery in industrial chemical and related processes (“chemical process engineers”); 2) development of new or adapted substances for products ranging from foods and beverages to cosmetics to cleaners to pharmaceutical ingredients, among many other products (“chemical product engineers”); and 3) development of new technologies such as fuel cells, hydrogen power and nanotechnology, as well as working in fields wholly or partially derived from Chemical Engineering such as materials science, polymer engineering, and biomedical engineering.