The adsorption of CO on Pd/Al2O3/Ta(110) model catalysts was studied using infrared reflection adsorption spectroscopy (IRAS) for two different Pd coverages, corresponding to 25-30 and 60-70 Angstrom average particle sizes. Striking similarities between the IRAS data for the larger particles and Pd single crystals indicate that the particles are comprised predominantly of [111] and [100] facets. The isosteric heat of adsorption of CO extrapolated to zero coverage was determined to be 38.9 kcal/mol on the 60-70 Angstrom particles. IRAS and Auger results provide evidence of CO dissociation on the smaller particles.