Reactions of silicon dioxide with ammonia molecules have been studied by matrix isolation infrared absorption and density functional theoretical calculations. Silicon dioxide molecules were prepared by reactions of laser-ablated silicon atoms with molecular oxygen in excess argon. When ammonia molecules were added to the reagent gas, the silicon dioxide-ammonia complex was produced spontaneously upon annealing. Broadband UV-visible photolysis decomposed the SiO2-NH3 complex and produced the H2NSiOOH molecule. The potential energy surface along the reaction path leading to the observed products has also been calculated.