The major products of the thermal decomposition of methyl formate in the gas phase are CH3-OH, CH2O, and CO. Experimental studies have proposed that the mechanism to describe these observations involves two key steps: (1) unimolecular decomposition of methyl formate to yield CH3OH + CO, followed by (2) thermal decomposition of methanol to yield CH2O + H-2. The present study shows that there exists an alternative mechanism that is energetically more favorable. The new mechanism involves two competing parallel unimolecular decomposition pathways to yield the observed major products.