The core of the coin features an image of a honeycomb symbolising the European Union. The beehive consists of twenty-seven cells, each comprising a star as a symbol of a European Union Member State. Next to the beehive, in the lower semi-circle, there is a square, a symbol of the Republic of Croatia, which is about to be incorporated into the beehive as the twenty-eighth cell, comprising a star - a new full member of the European Union.

The inscription "Treaty of Accession of the Republic of Croatia to the European Union" is laid out circularly within the ring of the coin. The lower central part of the ring bears the date "9 XII 2011".

The central part of the coin's core carries the designation of the nominal value 25. Within the numeral outlines, the figure of a pine marten running towards the right is shown; the marten's body is integrated with the numeral denoting the nominal value. In the bottom, central part of the coin's ring the coat of arms of the Republic of Croatia is impressed. A blooming laurel branch is placed in a semicircle on the left to the coat of arms, while a common oak branch with fruits is on the right. The top part of the ring carries the semicircular inscription The Republic of Croatia.

The word "kuna" means "marten" in Croatian since it is based on the use of marten pelts as units of value in medieval trading.

The martens are slender, agile animals, adapted to living in taigas, and are found in coniferous and northern deciduous forests across the Northern Hemisphere. They have bushy tails, and large paws with partially retractible claws. The fur varies from yellowish to dark brown, depending on the species, and, in many cases, is valued by fur trappers.

The coat of arms of the Republic of Croatia consists of one main shield and five smaller shields which form a crown over the main shield. The main coat of arms is a checkerboard (chequy) that consists of 13 red and 12 silver (white) fields. It's also informally known in Croatian as šahovnica ("chessboard", from šah, "chess"). The five smaller shields represent five different historical regions within Croatia.