This study investigates the characteristics of pyrolysis char/coke and elemental morphological changes on surface of char/coke produced, during co-pyrolysis of seaweed (EN) and rice husk (HU) at various temperatures through XPS, FTIR and SEM analysis methods. Analysis of pyrolysis products including by-products will help to partly explore co-pyrolysis synergistic mechanisms of the seaweed and rice husk. Thus, fast pyrolysis of EN and HU was conducted in a fixed bed reactor. Coke/char from the individual pyrolysis of EN and HU respectively at different temperatures, and those from co-pyrolysis of EN and HU (1:1) at 550 degrees C, were analyzed. Results revealed that the co-pyrolysis process has synergistic effects. Moreover, the release of nitrogenous substances was found to be inhibited by addition of HU at low temperature (<190 degrees C) range. It was also observed that co-pyrolysis of EN with HU does not only facilitates pyrolysis of aliphatic C-O functional groups at the middle temperature range, but also contributes to the cleavage of ether bonds of some water-soluble polysaccharides at high temperature (320-550 degrees C) level, hence generating aromatic compounds. Besides, the analysis of pore structures, pore size distributions and fractal dimensions of pyrolysis char/coke also show that the co-pyrolysis process has a synergistic effect. (C) 2018 Elsevier Ltd. All rights reserved.