This study aims to investigate the co-pyrolysis mechanism of Enteromorpha (EN) and rice husk (HU) through thermogravimetry coupled with mass spectrometry (TG-MS), pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) and fixed-bed experiments. Significant synergetic effects have been observed during the co-thermochemical conversion process, which not only improved the pyrolytic behaviors but also influenced the products compositions. Thermal analysis results showed that the experimental weight loss rate was always higher than that of the theoretical value at the temperature range of 200-300 degrees C. The release temperature of H2O, CO2 and CH4 gases products shifted to 291 degrees C, higher than the single EN and it was in accordance with the derivative thermogravimetric (DTG) curves. This suggests that synergistic effect has a significant influence on the dehydration, the decarboxylation reactions, and fracture, restructuring of methoxy groups and carbon-carbon bonds. The bio-oil yields from the co-pyrolysis of EN and HU mixture reduced, and with addition of HU the bio-oil yield decreased from 30.95% to 29.16% and then increased to 34.12%. The difference of Py-GC/MS and gas chromatography-mass spectrometry (GC-MS) results of bio-oil revealed that the secondary reaction could reduce furans and saccharides but increase carboxylic acids and hydrocarbons. Moreover, the possible reaction path of co-pyrolysis has been given. (C) 2018 Elsevier Ltd. All rights reserved.