Ab initio molecular orbital calculations at the second-order perturbation theory (UMP2) and coupled cluster singles and doubles with corrected triples (CCSD(T)) levels with 6-311++G(d,p) and 6-311++G(3df,3dp) basis sets have been carried out to construct the potential energy surfaces related to the various reactions of the [CH2N] system, including H-2+CN, H+HCN, and HS-HNC in both lowest lying doublet and quartet electronic states. Barrier heights, vibrational wavenumbers, and moments of inertia were then utilized in the calculations of rate constants using a quantum Rice-Ramsperger-Kassel (QRRK) theory. The calculated total rate constant k(infinity) for the H+HCN reaction at 300 K is 2.2 x 10(7) cm(3) mol(-1) s(-1) and is suggestive of a slow reaction and it corresponds predominantly to the stabilization of the adducts. On the other hand, the HS-HNC reaction is calculated to be a pressure-independent fast reaction with a rate coefficient of 1.9 x 10(11) cm(3) mol(-1) s(-1) leading primarily to H+HCN dissociation products. The standard heat of formation of the H2CN radical is estimated to be Delta H-f,298(0) = 56 +/- 3 kcal/mol (57 +/- 3 kcal/mol at 0 K).