The exothermic reaction of potassium hydroxide with methanol leads in an equilibrium reaction to potassium methanolate and water (avoiding formation of highly inflammable hydrogen gas).

Impurities of the resulting potassium methoxide in methanol with metallic mercury can be eliminated by ultrafiltration.

Because of their simpler production and better handling for chemical purposes solutions of potassium methanolate ( 25 to 32% by weight) are preferably used, which were continuously withdrawn from the amalgam process.

[7][8] The main application of potassium methoxide is use as basic transesterification catalyst in biodiesel synthesis (as a 25-32% methanolic solution).

The optimum conditions for biodiesel production from canola oil are reported as being 1.59% by weight of potassium methoxide, a reaction temperature of 50 °C and a methanol/oil ratio of 4.5: 1.