Monte-Carlo Simulations of temperature programmed desorption (TPD) of adsorbed molecules on metal surfaces is presented. First order desorption (molecular adsorption) was considered by using a lattice gas model where two different adsorption sites, 'on-top' and 'bridge', were allowed. The three nearest neighbor lateral interactions between adsorbed molecules were accounted for. The results from the simulations have been compared to TPD experiments of CO on Pt(1 1 1) and CO on a La-Pt surface alloy. The parameter space has been explored in the vicinity of realistic parameter values for these two desorption systems. Relatively good qualitative agreement between experimental and simulated desorption spectra has been achieved. ((C)) 2004 Published by Elsevier Ltd.