Upon cooling to −150 °C (−238 °F) it transforms to a ferroelectric phase of orthorhombic symmetry, and the transition temperature shifts up to −50 °C (−58 °F) when hydrogen is replaced by deuterium.

Monopotassium phosphate is produced by the action of phosphoric acid on potassium carbonate.

Also, to be noted is KD*P, potassium dideuterium phosphate, with slightly different properties.

Highly deuterated KDP is used in nonlinear frequency conversion of laser light instead of protonated (regular) KDP due to the fact that the replacement of protons with deuterons in the crystal shifts the third overtone of the strong OH molecular stretch to longer wavelengths, moving it mostly out of the range of the fundamental line at approximately 1064 nm of neodymium-based lasers.

Monopotassium phosphate is also used as an ingredient in sports drinks such as Gatorade and Powerade.