Solid substrate cultivation (SSC) using lignocellulosic non-food feedstock, such as switchgrass, is an alternative for advanced biofuel production. Acetone-Butanol-Ethanol (ABE) fermentation in two stages using a sequential culture of microorganisms from the class Clostridia is an approach proposed to increase the butanol production. The goal was to test the efficacy of a sequential culture on high solid substrate cultivation in batch and continuous cultivation, and to evaluate conditions to optimize butanol production using switchgrass as substrate. Initial batch experiments were used to determine particle size effect, choice of solvent producer and pretreatment evaluation: The effect of particle size on gas production was surface area-dependent, 2 mm particle size of switchgrass was better fermented by clostridia than the other particle sizes. C. thermocellum improved switchgrass fermentation by C. beijerinckii. Moreover, C. saccharoperbutylacetonicum produced the highest butanol yield on glucose as substrate. The Fenton reaction was studied as a potential pretreatment for switchgrass. C. beijerinckii grew better on Fenton-treated material, but solvent production was low. The major conclusion of the continuous flow on SSC experiment was that there is no statistical difference in the effect of flow rate within the flow range tested.