Adsorption, desorption and decomposition of carbon monoxide on a Rh(210) surface have been investigated in the temperature range between 300 and 1100 K by combined temperature programmed static secondary ion mass spectrometry (TPSSIMS), X-ray photoelectron spectroscopy (XPS) and temperature programmed desorption (TPD). Following adsorption of CO at 300 K three different molecular binding states, alpha-1, alpha-2 and alpha-3, are formed and identified through TPD. Partial decomposition of CO(ad) takes place during heating. C(ad) and O(ad) build-up have been followed by monitoring the relative SIGMA-(n)Rh(n)X+/Rh(n)+ (n = 1, 2; X = O, C) cluster ion intensities in (TP)SSIMS. At higher temperatures, i.e., above 500 K, C(ad) and O(ad) recombine as evidenced by the occurrence of a beta-CO feature in TPD. This process is associated with a decrease of the SIGMA-(n)Rh(n)X+/Rh(n)+ ratios. Further support for partial CO decomposition on Rh(210) is obtained from XPS. Carbon and oxygen show up in C 1s and O 1s features at 283.7 and 530.1 eV, respectively. Their intensities are about 10% of those found for a saturated CO layer at 300 K. Only the alpha-3 state seems to be implicated in the decomposition process as low exposures to CO, for which only the alpha-3 state is occupied, lead to the same amount of carbon and oxygen as high exposures.