 The review discusses the use of acidic thermochemical pretreatment to facilitate enzymatic hydrolysis of cellulose in lignocellulosic feedstocks, which is typically followed by microbial fermentation. However, substances formed during the pretreatment process can inhibit both enzymatic hydrolysis and microbial fermentation steps. The review focuses on identifying inhibitors from lignocellulosic feedstocks and suggests methods to alleviate these problems, including chemical in-situ detoxification and improving the performance of bio-catalysts. This article was authored by Johnson Leif J., Alrickson Bjorn, and Nilverbrant Nils Olof.