The uptake and reaction kinetics of alpha-pinene and beta-pinene with H2SO4 solutions were studied over the composition range of 37.0-80.0 wt.% in this Letter. The measurements have identified the occurrence of reversible uptake and irreversible reaction in acid solution. The initial and steady-state uptake coefficients (gamma(i) and gamma(s-s)) were acquired for the first time, displaying a strong dependence on solution acidity, and beta-pinene is more reactive than alpha-pinene. Atmospheric implication was discussed based on the corresponding uptake coefficients, which demonstrates that this heterogeneous acid-catalyzed reaction might be a significant contributor to SOA loading in concentrated acidic aerosols. (C) 2010 Elsevier B. V. All rights reserved.