The literature on the application of life cycle assessment (LCA) to process industry products and particularly to chemical processes has been reviewed. The main purpose of an LCA is to provide a quantitative assessment of the environmental impact of products over their entire life cycle, with a view to making improvements. Application to processes, which are key parts of the life cycle, is important in the context of process design and development, and in the analysis of processing chains. Reference is made to some important techniques for environmental assessment which interface with LCA when evaluating processes. The essential features of the LCA methodology are reviewed and some specific difficulties in the application of LCA are identified and discussed. These difficulties include allocation of impacts to multiple products, the definition of system boundaries, the quality of data, temporal and spatial characteristics, and impact assessment methods. Consideration is given to the combined use of LCA with economic evaluations, which is important in the process industry context. Finally, some cases of the application of LCA to specific chemical processes are reviewed.