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Torrefaction of plant biomass has the capacity to produce a fuel with increased energy density and homogeneity, but there are reports that it changes the pelletizing properties of the biomass, making it more difficult to obtain high quality pellets. A parametric study was therefore conducted in which three key qualitative parameters, degree of torrefaction (250–300 °C), moisture content (0–10%) and pelletizing temperature (125–180 °C), were varied according to a five level fractional factorial design, also including particle size as a qualitative parameter. Pelletizing at 300 MPa (pellet densities: 1.0–1.2 mg/mm³) was undertaken using a single pellet press and the responses recorded were compression work (W_comp), maximal force to overcome static friction (F_max), kinetic friction work (W_fric), single pellet dimensions and strength. Small particles reduced W_comp and F_max, but increased strength. As expected, all other …