text: The classic method for obtaining bismuthyl salts was the treatment of bismuth oxide () with nitric acid. This reaction produces bismuthyl salts such as BiO(NO and BiO(OH)(NO) as end products. The same bismuthyl salts precipitate when strongly acidic solutions of various bismuth compounds are diluted.
  The formation of bismuthyl was also considered to be a process that constantly occurs as a result of hydrolysis. Thus, bismuth nitrate, Bi(NO</small> is often formed.
  Bismuthyl chloride (BiOCl) is readily soluble in hydrochloric acid. Moreover, this process, like nitrate, proceeds through a reversible reaction; a shift of the reaction to the left or right also occurs along the line of hydrolysis, depending on the relative amount of water and the (residual) hydrochloric acid present. Adding water to a slightly acidic solution of ВіСl immediately causes the appearance of a white precipitate of basic bismuth chloride, BiOCl. When hydrochloric acid is added, the precipitate dissolves again, but it immediately falls out when more water is added. All other bismuth compounds behave in aqueous solutions similarly to chloride.
  At elevated temperatures, the vapors of the metal combine rapidly with oxygen, forming the yellow trioxide, Bismuth(III) oxide|. When molten, at temperatures above 710 °C, this oxide corrodes any metal oxide and even platinum. On reaction with a base, it forms two series of oxyanions: , which is polymeric and forms linear chains, and . The anion in  is a cubic octameric anion, , whereas the anion in  is tetrameric.
  In addition to bismuthyl itself, thiocompounds corresponding to bismuthyl salts are also considered indicative for the chemistry of bismuth, for example, gray thiobismuthyl chloride with the formula BiSCl and others similar to it. These substances, unlike bismuthyl salts, are very stable with respect to water, and can be easily prepared by the action of hydrogen sulfide gas on the corresponding bismuth trihalide.