The thermodynamics and kinetics of adsorption of the redox-active tris(bipyridyl)ruthenium(II) pendant poly(amido amine) (PAMAM) dendrimers and bis(terpyridyl)ruthenium(II) pendant PAMAM dendrimers (generations 0, 1, 2, 3, and 4) have been studied using electrochemical methods. All of these metallodendrimers adsorb onto Pt electrodes at +0.8 V vs Ag/AgCl where the Ru sites of the dendrimers have 2+ charges and the adsorption thermodynamics are well characterized by the Langmuir adsorption isotherm. The kinetics of adsorption were found to be activation controlled with the rate constant decreasing with decreasing dendrimer generation. Electrochemically determined coverages were significantly larger than calculated values determined from the dimensions of the metallodenrimers obtained from molecular modeling. These comparisons suggest that upon adsorption, the dendrimers appear to compress to dimensions significantly smaller than those calculated.