The Reichsmünzordnung (German: [ˈʁaɪçsˌmʏntsˌʔɔʁdnʊŋ], "imperial minting ordinance") was an attempt to unify the numerous disparate coins in use in the various states of the Holy Roman Empire in the 16th century.
A first Reichsmünzordnung was issued by Charles V in 1524 at Esslingen, declaring the Cologne Mark as the general standard for coin weights.
The definition of a gold and a silver coin (Gulden vs. Guldengroschen) of equivalent value was problematic, as the value of the gold coin tended to rise above that of the silver one, and soon the Gulden was de facto traded at more than the official 72 Kreuzer.
This led to the abolition of the official standard linking of gold and silver coins in 1559 under Ferdinand I.
In 1566, the Diet was forced to recognize the new status quo and introduced the Reichstaler (at 29.23 grams of 88.9% silver) as the official coin of the empire.