Liquid hot water pretreatment is considered to be a promising method for increaing biomass digestibility due to the moderate operational conditions without chemical additionA necessary step towards the scalability of this pretreatment process is performing pilot plant triaUpscaling was evaluated with a scaling factor of 500, by using 50 mL in the laboratory and 25 L in pilot plant batch reactor. Pretreatment times were varied from 30 to 240 min, and temperatures usewere 180–188◦ C, while applying similar heating profiles at both scales. The initial mass fraction poplar wood chips ranged from 10% to 16%. Liquid hot water pretreatment at laboratory and pilscale led to analogous results. The acetic acid analysis of the liquid and solid fractions obtained aftpretreatment indicated that complete deacetylation of poplar biomass can be achieved.@en