The central part of the coin core features two squares symbolising the Republic of Croatia, placed one above the other with touching corners. The squares' edges, shown as if in motion, are formed by three lines, modelled after the Croatian wattle. The loose lines in the right upper corner of the lower bigger square are a symbol Croatia's openness towards the European Union. These lines stretch over to the coin ring embossed with twelve EU stars, which are interlaced by the Croatian wattle, as a symbol of Croatia's determination to become an integral part of the EU. Positioned centrally along the lower edge and bordered by a small square on the left and a small star on the right is the date "18 June 2004". The inscription "The Republic of Croatia Candidate for being a member of European Union" continues from the date to the right, closing the circle on the coin. Above the square, in the ring, it is written the signature of the engraver (DM).

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.