Mechanisms for the pyrolysis of formic acid in the gas-phase catalyzed by w
ater dimer or formic acid itself are proposed for the first time. At the B3
LYP/6-311 ++G(3df,3pd)//B3LYP/6-311++G(d,D) level, the barrier heights for
both dehydration and decarboxylation reactions are revealed to be significa
ntly lower than previously reported values, implying the importance of the
catalytic effect of (H2O)(2) and HCOON.