Features of the ground-state potential energy surface of formaldehyde relevant to its dissociation to H-2 and CO were analyzed by means of ab initio calculations. The multiconfigurational self-consistent field (MCSCF) calculation gave a critical energy of 83.22 kcal/mol. Accurate structures are presented for H2CO(X(1)A(1)) and the saddle point. The reaction path was determined and the coupling between reaction coordinate and normal modes was analyzed along it, with two different levels of calculation (Hartree-Fock and MCSCF). Using these data, the transition state was located and the rate constants were calculated for the temperature range 200-4500 K using the generalized transition state theory.