A method for manufacturing biomass microspheres is introduced. Biomass microspheres between 100 and 400 mu m in diameter were produced from crystalline cellulose, switchgrass, and tall fescue using spray drying. The biomass microspheres were characterized using X-ray computed tomography (XCT), thermal gravimetric analysis (TGA), and real-time optical imaging: density, pore structure, and size effects were studied. Dynamic shrinkage was video-captured using a CMOS camera and parallel (paired, side-by-side) weight loss experiments were performed using TGA. The combined data was used to correlate the extent of pyrolysis to gross morphological change (shrinkage). The results show that manufactured biomass microspheres are uniform and that, in the absence of heat and mass transport limitations, pyrolysis shrinkage is an intrinsic property dependent only upon the final processing temperatures.