Palladium catalyst samples were prepared upon bacterial. biomass Supports (Gram-positive A. oxidans and Gram-negative R. capsulatus) and tested in the partial hydrogenation of 2-butyne-1,4-diol to 2-butene-1,4-diol. The objectives of the study were to assess the effects of operating conditions in the stirred autoclave upon the reaction conversion and selectivity and to compare the biologically supported palladium (BioPd) catalyst performance with that of a conventionally Supported catalyst. Variables investigated included solvent, stirring speed, and catalyst metal loading. A maximum selectivity toward 2-butene- 1,4-diol of 0.98 was observed in a solvent composed of 5% isopropyl alcohol (2-propanol) in water at it conversion of 75% 2-butyne-1,4-diol for the Pd/A. oxidans catalyst. The P&R.capsulatas catalyst showed a maximum selectivity of 1.0 at a conversion of 62.6%. Concentration profiles of the different hydrogenation products were fitted using a Langmuir-Hinshelwood expression, which showed a higher fitted adsorption constant of 2-butyne-1,4-diol in a 5% 2-propanol/water solvent, compared with pure 2-propanol, suggesting that adsorption is stronger in the mixed solvent. At a typical catalyst loading of 0.29 g/L (Pd/R. capsulatus), analysis of the mass-transfer steps in the reactor showed that similar to 63% of the resistance to mass transfer lies at the catalyst (liquid-solid) particle and similar to 37% lies at the gas bubble interface. BioPd was proven to be a highly selective catalyst for partial hydrogenation reactions and has the advantage that it can be prepared inexpensively from metal-waste-bearing solutions.