 The review discusses how acidic thermochemical pretreatment of lignocellulose feedstocks is typically followed by an enzymatic hydrolysis step, but substances formed during the pretreatment can inhibit both enzymatic hydrolysis and microbial fermentation. The review focuses on identifying inhibitors from lignocellulose feedstocks and suggests methods to alleviate inhibition problems, such as chemical in-situ detoxification and improving the performance of bio-catalysts. This article was authored by Johnson Leafj, Alrex and Bjorn, and Nylvabrant Nylzolov.