Praseodymium(III) chloride is the inorganic compound with the formula PrCl3.

It is a blue-green solid that rapidly absorbs water on exposure to moist air to form a light green heptahydrate.

[3][6] Praseodymium(III) chloride is Lewis acidic, classified as "hard" according to the HSAB concept.

[3] PrCl3 forms a stable Lewis acid-base complex K2PrCl5 by reaction with potassium chloride; this compound shows interesting optical and magnetic properties.

For example, praseodymium(III) phosphate and praseodymium(III) fluoride can be prepared by reaction with potassium phosphate and sodium fluoride, respectively: When heated with alkali metal chlorides, it forms a series of ternary (compounds containing three different elements) materials with the formulae MPr2Cl7, M3PrCl6, M2PrCl5, and M3Pr2Cl9 where M = K, Rb, Cs.