BACKGROUND: A central composite experimental design and multiple regression were used to model the production of pulp and paper sheets from a Paulownia fortunei x tormentosa x elongata trihybrid clone. Also, the same experiments were carried out with the solid phase after autohydrolysis of the raw material. RESULTS: The results were compared with those obtained from the solid phase remaining after autohydrolysis of the raw material with a view to optimizing the use of hemicelluloses and cellulose by fractionation. Pulp and paper sheets from the trihybrid clone surpass those from other Paulownia species such as P. fortunei and P. elongata in physical properties such as tensile index (11.6-49.1 Nm g(-1)), burst index (0.23-2.41 MPa m(2) kg(-1)), tear index (0.71-3.03 mN m(2) g(-1)) and intrinsic viscosity (427-958 cm(3) g(-1)). CONCLUSIONS: The solid phase obtained by autohydrolysis of the Paulownia trihybrid provides pulp and paper sheets comparable in strength-related properties with those of pulp directly produced from the raw material, but using substantially milder operating conditions and with the added advantage that the autohydrolysis treatment provides highly valorizable liquor. (C) 2011 Society of Chemical Industry