Hydrodeoxygenation (HDO) of lignin-derived pyrolysis oil has received signifi cant attention as a potential technology for

replacing conventional petroleum-based fuels and chemicals. Ru-based HDO catalysts are in the limelight as HDO catalysts

since they exhibit excellent catalytic activity while being cost-eff ective compared to other noble metal-based catalysts.

Various studies have reported Ru-based catalysts used in the HDO of lignin-derived pyrolysis oil and its model compounds,

and a variety of strategies have been utilized to tune the catalytic properties to enhance the performance and advance the

understanding of the HDO reaction. This review discusses the recent publications on Ru-based catalysts used in the HDO of

lignin-derived pyrolysis oil and its model compounds. Additionally, an overview of HDO reactions and the characteristics

of HDO catalysts were summarized, and the general advantages of Ru catalysts, which are extensively used as attractive

catalysts in the various reactions, are introduced. Various factors, including reaction conditions, support materials, and

promoters, that can aff ect the performance of Ru-based HDO catalysts are organized, and the strategies utilized to modify

the properties of the catalysts are categorized. Finally, the areas that require further development such that Ru-based HDO

catalysts can overcome the remaining challenges are outlined.