We have extended our studies on the use of Hyper–Rayleigh Scattering spectroscopy (HRS) as a tool for studying surface chemical characteristics of nanosize AgBr particles to include: (a) metathetical reaction of iodide ion with AgBr; (b) formation of the AgBr-Ag carboxylate interface; (c) heterogeneous reduction of AgBr to Ag(0); (d) initial stages of sulfur sensitization; and (e) of gold sensitization. By coupling measurement of hyperpolarizability changes concurrent with these various reactions with characterization of the wavelength dispersion of HRS, we inferred formation of a separate AgI phase even at low levels of conversion of AgBr, as well as a role for adsorbed silver ions in surface second harmonic generation from AgBr itself. Similarly we showed that undecanoate anion reacts reversibly with the AgBr surface and that the adsorbate, presumably silver undecanoate, introduces a new characteristic electronic transition, resonant with second harmonic scattering, at 2.97 eV. Carboxylate anions also appear to catalyze oxidation of silver(0) species at the AgBr surface. Thioacetamide, a prototypical sulfur sensitizing reagent, chemisorbs reversibly to AgBr, producing a dramatic enhancement of surface hyperpolarizability. Some reduction of AgBr to silver(0) seems to accompany introduction of this reagent under our conditions. Inference of formation or bleaching of silver(0) species hinges on assignment of an electronic transition at ca. 470 nm, resonant with HRS, which is observed on addition of dimethylamineborane complex to AgBr, to silver(0) clusters. Gold, as KAuCl₄, was observed by our probes to react with AgBr only in the presence of silver(0); we infer disproportionation of Au(I) at the silver(0) centers, and incorporation of gold into the silver clusters.