The absorption of elemental Hg vapor into aqueous solution containing Hg(II) was measured in a stirred cell contactor at 25 and 55 degrees C. In 0.8 M HNO3, the reaction is first-order in Hg and Hg(II), respectively. The overall second-order rate constant is given by k(2) = 2.90 x 10(9) x exp(-1765/T). In 0.8 M HNO3 with the addition of H2O2, the reaction is first-order in Hg, H2O2, and Hg(II), respectively. The overall third-order rate constant is given by k(3) = 2.13 x 10(23) x exp(-10110/T). The addition of Fe2+ or Fe3+ has no immediate effect on mercury removal. In 0.8 M HNO3 with the addition of K2Cr2O7, the reaction is first-order in Hg, Cr2O7-, and Hg(II), respectively. The overall third-order rate constant is 4.3 x 10(8) M-2 s(-1) at 25 degrees C. For mercury absorption in Hg(II) obtained by HgCl2 injection, the presence of HNO3 greatly enhanced Hg absorption. H2SO4 had a comparable positive effect while HCl had a negative effect. Succinic acid-NaOH buffer solution greatly enhanced Hg absorption in Hg(II), but NaHCO3-NaOH inhibited Hg absorption in Hg(II). MnSO4 mildly enhanced Kg absorption in Hg(II). At MnSO4 concentrations lower than 0.22 M, a constant overall third-order rate constant of 4.4 x 10(7) M-2 s(-1) was obtained at 25 degrees C. NaCl, MgSO4, FeCl3, CaCl2, and MgCl2 all inhibited Hg absorption in Hg(II). Under most conditions, oxygen in the gas phase did not have any effect on Kg absorption in Hg(II). However, oxygen had a positive effect on Hg absorption in Hg(II) when HCl or NaHCO3/NaOH was present in the solution.