The time separation of experimental surface energy on Pt–Rh bimetallic catalysts, together with the time-independent rate constants for adsorption and desorption of O 2 , CO, and CO 2 on them, is described, applying the reversed-flow version of inverse gas chromatography. The standard free energy of adsorption ΔG⦵ and its probability density function over time, together with the geometrical mean of the London parts of the total surface free energy (γ L 1 γ L 2 ) 1/2 of the adsorbed probe and the solid surface, accompanied by the relevant probability density functions over time are also calculated. The time-resolved phenomena lead to quite varying values of ΔG⦵, (γ L 1 γ L 2 ) 1/2 , and the distribution functions as time passes, their maximum values being given by the catalyst containing a Pt:Rh = 3:1 weight ratio of the active phase for all adsorbed gases. The conclusion is reached that the surface energy measured as described can be used as a good measure for catalyst characterization.