Nanometer sized gold and silver clusters protected with 2-mercaptobenzothiazole monolayers have been prepared and characterized by various spectroscopic methods. Optical absorption spectra show features assigned to charge-transfer excitation between the monolayer and the cluster, in addition to a red shifting and reduction of plasmon absorption. The monolayers on clusters are compared with the corresponding 2D-monolayers investigated previously. The dominant adsorbate geometries on these clusters are different. Whereas the temperature dependent dynamics are minimal for 2D-SAMs, they are significant for monolayers on 3D surfaces, which is attributed to the decreased packing density on the cluster surfaces. The thermal stability of these monolayers is high and comparable to that of alkanethiolate monolayers. The monolayers undergo irreversible structural changes upon heating, which have been studied by differential scanning calorimetry and IR spectroscopy.