structural:expansion, structural:summarization
Structure

At higher temperatures, solid KOH crystallizes in the NaCl crystal structure. The OH group is either rapidly or randomly disordered so that it is effectively a spherical anion of radius 1.53 Å (between Cl and F in size). At room temperature, the OH groups are ordered and the environment about the K centers is distorted, with K −OH distances ranging from 2.69 to 3.15 Å, depending on the orientation of the OH group. KOH forms a series of crystalline hydrates, namely the monohydrate KOH · H O, the dihydrate KOH · 2 H O and the tetrahydrate KOH · 4 H O.