Abstract Co-pyrolysis of coke bottle (CB) with sawdust/cellulose/lignin was conducted at 700 °C in this study, aiming to understand the potential influence of interactions of the volatiles of the varied origins on properties of the char. The results indicated that the interaction of volatiles from CB with that from biomass enhanced cross-polymerization of the volatiles, decreasing the formation of gases while enhanced the formation of both char and oil. The cross-interactions of the intermediates also diminished the formation of π-conjugated organics. In addition, the varied volatiles from the pyrolysis of cellulose, lignin, or sawdust interacted with that from CB and affected the properties of char in different ways. The char from the co-pyrolysis of sawdust/CB was more aliphatic, and had a higher oxygen content (7.3%) and higher polarity but lower thermal stability. Additionally, the thermal stability, crystallinity as well as the evolution of functionalities of char versus increasing temperature were also significantly affected by the cross-interactions of the volatiles.