Abstract. Liquid-phase semihydrogenation of phenylacetylene under mild conditions has been investigated on a series of solvothermal-derived nano-TiO2 supported Pd catalysts with various TiO2 crystallite sizes in the range of 9–23 nm. As revealed by CO chemisorption and transmission electron microscopy, all the catalysts exhibited strong metal–support interaction (SMSI) when reduced at 5…