Treatment of zirconium oxide with sulphate ions forms a highly acidic, or superacidic catalyst; sulphated zirconia. This catalyst has been found previously to be highly applicable to a range of reactions including acylation alkylation, isomerization, cracking and dehydration at temperatures in the range 150-200degreesC. These relatively low-temperature reactions offer potential in the field of bio-oil catalytic upgrading. Here zeolite catalysts have been used predominantly, but with associated problems due to the high reaction temperatures related with their use. The paper describes the processes involved in optimization of a process for the catalytic upgrading of a bio-oil produced by slow pyrolysis of pine wood. Copyright (C) 2002 John Wiley Sons, Ltd.