Although the compound can be found in mineral form, AgBr is typically prepared by the reaction of silver nitrate with an alkali bromide, typically potassium bromide:
AgNO3(aq) + KBr(aq) → AgBr(s)+ KNO3(aq)
Although less convenient, the salt can also be prepared directly from its elements.
Modern preparation of a simple, light-sensitive surface involves forming an emulsion of silver halide crystals in a gelatine, which is then coated on a film or other support. The crystals are formed by precipitation in a controlled environment to produce small, uniform crystals (typically < 1 μm in diameter and containing ~1012 Ag atoms) called grains