Bio-char is a by-product from thermochemical treatment of biomass and has been identified as an energy condensed product with a comparable heating value as commercial coal. However, the combustion of such solid product as an energy resource is only a preliminary application. It is highly possible to convert bio-char, which always has a condensed aromatic and porous structure to various high-value products. The investigations of the structures and formation pathways for the bio-char are very important to any future applications. In this study, six different biomass components, including cellulose, lignin, and tannin, and three whole biomasses?pine wood, pine residue, and pine bark?have been used to produce bio-char at 400, 500, and 600 �C. Solid-state NMR and FT-IR have been employed in this study to characterize the structures for the bio-chars. The results indicated that the bio-chars produced from lignin contained some methoxyl groups, and the bio-chars produced from tannin contained significantly higher amount of phenolic hydroxyl groups. Compared to the bio-chars produced from pine wood and residue, the bio-chars produced from pine bark contained more aromatic C?O bonds, and aliphatic C?O and C?C bonds, which may be due to the significantly higher amount of lignin and tannin in the pine bark. Furthermore, the elevated amounts of aromatic C?O and aliphatic C?O and C?C bonds in the bio-chars from pine bark appeared to be completely decomposed at 600 �C.