Abstract: Bond order conservation-Morse potential approach has been used to study the mechanism of decomposition for HCOOHon Ag(111), Ni(111) and Fe/W(110) surface in the two cases of extremely low and higher coverages.The following results have been obtained; In the first case, HCOOHdecomposed via intermediate (HCOO_(s)), which proceeds following the order Ag<Ni<Fe/Weasily, over Fe/W HCOOoxidizes the surface and the bond scission of C-Hand C-Ohas a small energy barrier difference.In the second case, the mechanism does not change over Ag, but changes over Ni,Fe/W.Two HCOOHmolecules form a surface complex (HCO_(s) * HCOO_(s)) with the loss of water and then decompose further.Over Ni the decomposed reactions have low energy barriers and can show an autocatalytic behavior.

Key words: Mechanism of decomposition for HCOOH, Bond order conservation, Metal surfaces