The effects of temperature, CO(ad) surface coverage, and electrode potential on the desorption of CO(ad) from Pt film electrodes in 0.5 M H(2)SO(4) have been investigated by electrochemical in situ FTIR spectroscopy under an attenuated-total-reflection configuration (EC-FTIRS). The major findings are: (i) When theta(rel)>or= 0.53 (theta(CO) is the relative CO(ad) coverage), CO(ad) desorption takes place at T > 40 degrees C (as confirmed by the decrease in both of the C-O(L) stretching frequency as well as the CO(ad) stripping charge), and when theta(rel) is below 0.39, no CO(ad) desorption is observed at temperatures up to 70 degrees C; (ii) A slight increase in CO(ad) desorption rate with electrode potential from 0.1 to 0.3 V and fast adsorption/desorption equilibrium in solution saturated with CO are observed; (iii) From the temperature-dependent changes in CO(ad) surface coverage, the activation energies for CO(ad) desorption are determined to be in the range of 104 and 117 kJ mol(-1), which increases with decreasing CO(ad) coverage.