The Australian fifty cent coin is the largest commonly circulating Australian coin.  It was initially produced in 1966 as a round, 80% silver coin but was quickly removed from circulation because the silver value exceeded the face value.  In 1969 the 50c made a re-appearance as a large, unusual dodecagonal (12 sided) coin bearing the portrait of the English monarch on one side and the Australian coat of arms on the other.

The Australian 50c coin had been released with a large number of reverse designs for circulation and the collector market and this included the first commemorative Australian decimal coin when the Captain Cook 50c was released in 1971.