This study was concerned with the effects of aerosols on the kinetics of disappearance of atomic oxygen. Atomic oxygen was generated by a 2450 MHz microwave discharge, and the kinetics of disappearance measured in a fast flow system using N0₂ titration. The recombination coefficient, for heterogeneous wall recombination was determined for clean Pyrex, H₂SO₄ coated wall, and (NH₄)₂SO₄ coated wall. The values of γ were 4.97 x 10^-5, 2.05 x 10^-5, and 1.90 x 10^-5 respectively. A rapid exothermic chemical reaction was found to occur between atomic oxygen and NH₄C1; the products, as determined by mass spectrometry, were NH₃, NO, H₂O, HC1. An NH₄Cl aerosol was generated by gas phase reaction of NH₃(g) with HCl(g), The aerosol particles were approximately spherical and nearly monodisperse with a mean diameter of 1.6 ± .2 μm. The rate constant {k_AERO) for the disappearance of atomic oxygen in the presence of an NH₄Cl aerosol was measured. For an aerosol concentration of 4.75 x 10³ µg/m³. a value of k_AERO = 2.75 ± .5 sec^-1 was found, / M.S.