The liquid phase hydrogenation of phenylacetylene on pumice supported palladium catalysts with a large range of metallic dispersions (14% < D-x < 62%) has been carried out in a mechanically stirred glass reactor where any mass transfer effects are eliminated. A five parameters mathematical model has been used to analyze the kinetics. Three basic routes, involving only surface species in the rate determining steps, contributed to the mechanism of the reaction. The hydrogenation of phenylacetylene to styrene, with the pumice supported palladium catalysts, shows good activity and selectivity. The reaction is structure insensitive in the whole range of the considered dispersions, in contrast to that with other Pd catalysts on more traditional supports, which show a marked decrease in activity and selectivity when dispersion of the metallic phase is higher than 20%.