We have investigated the co-adsorption of NH3 and SO2 on the quartz(0 0 0 1) surface by TPD and RAIRS. A surface complex is formed as a result of various relative exposures of NH3 and SO2, irrespective of dosage order. However, the relative molecular composition of the complex is dependent on the dosage order. Higher desorption temperatures of NH3 and SO2 from the co-adsorbed systems, as compared with the isolated adsorbates, demonstrate mutual stabilization in the adlayer. Formation of hydrogen bonds between NH3 and SO2 is suggested based on the strong decrease in IR cross-section of the symmetric deformation and asymmetric stretch modes of NH3 upon co-adsorption of SO2 and of the symmetric stretch mode of SO2 upon co-adsorption of NH3. (C) 2011 Elsevier B. V. All rights reserved.