The interactions of pyrolyzed and calcined bio-cokes with three coal tar pitches of different properties were studied using a sessile drop test at 170 degrees C. A model was employed to characterize and quantify the spreading and penetration of pitch into bio-coke bed. The pyrolyzed bio-cokes were produced from softwood materials by heat treatment at 426 degrees C. The calcined bio-cokes were produced by calcining the pyrolyzed bio-coke at 1200 degrees C. Optical microscope, SEM/EDS, XRD, and FTIR techniques were used to analyze the coke-pitch interface and study their interaction mechanisms. The results show that the wettability of bio-coke is related to both pitch and coke properties. It is found that the presence of small amount of uniformly distributed small size quinoline insolubles (QI) in pitch seems to help pitch spread and penetrate into the bio-coke bed. Besides, calcination changes the chemical structure of bio-coke, enriches its carbon (C%) content, increases its crystalline length (Lc), and lowers its wettability by pitch. (C) 2016 Elsevier Ltd. All rights reserved.