The hydrogen abstraction reaction CH2O + NH2 --> CHO + NH3 has been studied using direct ab initio dynamics method. All of the information along the minimum energy path (MEP) was calculated at the UMP2/6-311+G(d, p) level of theory. Energetic data along the MEP were further refined using the scheme G2 with the UMP2/6-311+G(d, p) optimized geometries. The barrier heights for the forward and reverse reactions were obtained as 5.89 and 24.44 kcal/mol, respectively. Reaction rate constants and activation energies were calculated for the temperature range 250-2500 K by the improved canonical variation transition state theory (ICVT) incorporating a small-curvature tunneling correction (SCT), The rate constant at the room temperature was predicted to be 5.25 x 10(-17) cm(3) molecule(-1) s(-1), which is about 2 orders of magnitude smaller than that of the hydrogen abstraction reaction of acetaldehyde with aminogen.