Pyrolysis was demonstrated to investigate the thermal decomposition characteristics and potential of lignin-rich cotton by-products cotton exocarp (CE) and spent mushroom substrate consisted of cotton by-products (MSC) for biorefineries. The chemical component and structure alteration of CE and MSC was found to affect their thermochemical behaviors. The bio-oil yield from CE was 58.13 wt% while the maximum yield from MSC was 45.01% at 600 degrees C. The phenolic compounds obtained from CE and MSC were 33.9% and 39.2%, respectively. The yield of acetic acid from MSC between 400 and 600 degrees C was about 30-38% lower than that from CE, which suggests the high quality of bio-oil was obtained. Biochar from MSC via slow pyrolysis had a high mass yield (44.38 wt%) with well-developed pore structure. (C) 2016 Elsevier Ltd. All rights reserved.