Quote Originally Posted by gainer View Post
One can make a solution of KOH from K2CO3 and Ca(OH)2 in water. A slight excess of Ca(OH)2 would assure no carbonate in the solution, but perhaps a little of the calcium hydroxide. Any comment?
Well, if you are on desert island or you don't mind calcium in your potassium hydroxide, that's one way.

Industrially, my Hawley's Condensed Chemical Dictionary states that potassium hydroxide is manufactured by the electrolysis of potassium chloride. Then residual sulfur compounds can then be removed by the addition of potassium nitrate to the fused caustic. It can then be further purified by solution in alcohol, filtration, and finally evaporation.