The coin is the first to use a new portrait of the Queen which will be used on all coins produced from this month.
On the other side is a "celebratory arrangement" of the 12 stars of Europe, depicted as though they are part of a giant firework display.
The 50p piece, the same size as the smaller coin introduced last September, also marks the 25th anniversary of the UK's entry into what was then the European Economic Community. It will carry the dates 1973 and 1988.
The stars design is the work of John Mills, president of the Royal Society of British Sculptors, who has designed previous celebratory coins such as those for the 1996 European Football Championships held in England and the 50th anniversaries of D-Day and the end of the Second World War.
The design was chosen from more than 160 submitted by more than 40 artists.
The new royal portrait, created by Ian Rank-Broadley, is the fourth portrait of the Queen to appear on circulating coins in her 45-year reign.
The Royal Mint will produce five million of the commemorative 50p coins. It was also confirmed yesterday that on 28 February the older, heavier version of the 50p will cease to be legal tender.Reuse content