A detailed theoretical survey on the. triplet potential energy surface (PES) for the CH + NO2 reaction is carried out at the B3LYP and CCSD(T) (single-point) levels in order to gain a deeper mechanistic knowledge of this important radical reaction. Thirty-eight minimum isomers and 107 transition states are located. It is shown that the CH and NO2 radicals can be brought together barrierlessly via the triplet PES to form the initial N-attack adduct HCNO2 (1) that lies 50.6 kcal/mol below the reactant R. Subsequently, the most feasible channel is the direct O-extrusion of I to produce P-6 (HCNO + O-3) with the barrier 31.2 kcal/mol. The, less competitive channel is a 1,3-H shift conversion of 1 to the branched isomer HON(O)C (10) (34.2 kcal/mol below R) With a barrier 37.1 kcal/mol, which can directly dissociate to product P-9 (CNO + OH) with a small barrier 9.0 kcal/mol. However, the oxygen-shift conversion of I leading to the very low lying isomers OC(H)NO (2) (2') that can directly dissociate to P, (HCO + NO) and then P-12 (H + CO + NO) needs a much larger barrier, 43.3 kcal/mol. This is in sharp contrast to the mechanism of the title reaction via the singlet PES (Tao; et al. J. Phys. Chem. A 2001, 105 3388) that the exclusive feasible channel proceeds via the almost barrierless oxygen-shift conversion of HCNO2 to OC(H)NO followed by formation of. HCO + NO (major), HNO + CO, and HON + CO (minor), each of which can take secondary dissociation to the final product H + CO + NO. Since all appropriate transition states and intermediates lie below R, the overall rate constant of the title reaction via the triplet PES is expected to be fast, as confirmed by the simple RRKM calculations (k(298K) = 5.14 x 10(-12) cm(3) molecule(-1) s(-1)). Since the predicted products of the title reaction via the triplet PES is completely different from that via the singlet PES, we feel that future experimental investigations on this radical reaction are desirable.