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The hydrolysis of CH 2 OO is not only a dominant sink for the CH 2 OO intermediate in the atmosphere but also a key process in the formation of aerosols. Herein, the reaction mechanism and kinetics for the hydrolysis of CH 2 OO catalyzed by the precursors of atmospheric aerosols, including H 2 SO 4 , H 2 SO 4 ···H 2 O, and (H 2 SO 4 ) 2 , have been studied theoretically at the CCSD(T)-F12a/cc-pVDZ-F12//B3LYP/6-311+G(2 df ,2 pd ) level. The calculated results show that the three catalysts decrease the energy barrier by over 10.3 kcal·mol -1 ; at the same time, the product formation of HOCH 2 OOH is more strongly bonded to the three catalysts than to the reactants CH 2 OO and H 2 O, revealing that small clusters of sulfuric acid promote the hydrolysis of CH 2 OO both kinetically and thermodynamically. Kinetic simulations show that the H 2 SO 4 -assisted reaction is more favorable than the H 2 SO 4 ···H 2 O- (the pseudo-first-order rate constant being 27.9-11.5 times larger) and (H 2 SO 4 ) 2 - (between 2.8 × 10 4 and 3.4 × 10 5 times larger) catalyzed reactions. Additionally, due to relatively lower concentration of H 2 SO 4 , the hydrolysis of CH 2 OO with H 2 SO 4 cannot compete with the CH 2 OO + H 2 O or (H 2 O) 2 reaction within the temperature range of 280-320 K, since its pseudo-first-order rate ratio is smaller by 4-7 or 6-8 orders of magnitude, respectively. However, the present results provide a good example of how small clusters of sulfuric acid catalyze the hydrolysis of an important atmospheric species.