Environmental and socioeconomic concerns impact the dependence on coal, resulting in increased thermochemical coconversion of coal and biomass. The efficiency of the thermochemical conversion process is controlled by the conversion of char. In this paper, the properties of copyrolysis char from coal blended with biomass are focused on, through a review of the literature. The properties of copyrolysis char can be influenced by the interaction between coal and biomass during the copyrolysis process. More than 80% of the research has reported that copyrolysis has synergistic effects on the surface morphology and reactivity of copyrolysis char. Possible synergies due to the differences in the structure and chemical composition of coal and biomass are discussed with some possible synergistic mechanisms. Recommendations grounded on research in the literature are suggested.