Abstract: Combining the advantages of hollow and mesoporous structures, hollow mesoporous fibers have great potential in the adsorption of macromolecules. Such fibers were fabricated by a wet-spinning method from a polymer mixture of polyacrylonitrile and alkali lignin. The effect of the composition of the solution in the coagulation bath on the microstructures of the hollow mesoporous fibers produced was investigated by SEM, TGA and nitrogen adsorption. Results indicate that the diameter and pore structure of the fibers were changed by the composition of the solution in the coagulation bath. By increasing the concentration of dimethyl sulfoxide, the average pore size of the fibers decreased from 45.3 to 24.4 nm while the outer diameter and porosity reached minima of 137.5 μm and 88.7%, respectively while the wall thickness reached a maximum of 20.3 μm. The fibers can be processed into hollow mesoporous carbon fibers because of their high carbon yield of 40%.