This work is based on the data collected during trials of a continuous steam explosion (SE) plant, with a treatment capacity of about 350 kg/h, including the biomass fractionation section. The energy and water consumption, equipment cost, and manpower needed to run this plant have been used as the base case for a techno-economic evaluation of productive plants. Three processing plant configurations have been considered: (I) SE pretreatment only; (II) SE followed by the hemicellulose extraction; (III) SE followed by the sequential hemicellulose and lignin extractions. The biomass treatment cost has been evaluated as a function of the plant scale. For each configuration, variable and fixed cost breakdown has been detailed in the case of a 50,000 t/y plant.