Portrait in left profile of Juan Carlos I surrounded by the inscription "Juan Carlos I King of Spain", date below.

Depicts the facial value and the coat of arms during the Spanish transition to democracy (1977–1981). The exact year of issuing is located in the stars on both sides of the word "UNA".

The Spanish coat of arms is composed of six other arms: castle of Castile, lion of León, stripes of Aragon, chains of Navarre, pomegranate flower of Granada and fleur-de-lis of the House of Bourbon. The escutcheon represents the currently reigning dynasty Bourbon-Anjou.

On either side of the coat of arms are the Pillars of Hercules, the mythological name given to the Straits of Gibraltar. The banner round the pillars is the national motto of Spain "Plus Ultra" which means "further beyond" in Latin, referring to the Americas and the former Spanish territories. Over the pillars are two crowns, one an Imperial Crown and the other a Royal Crown. King Charles I of Spain was also the Holy Roman Emperor Charles V, hence the Imperial Crown.

1978 variations:
• Royal Spanish Mint: long tilde over N in ESPAÑA.
• Chilean Mint: point-like tilde over N in ESPAÑA; 78 in star spaced.
• Royal Mint (UK): point-like tilde over N in ESPAÑA; 78 in star near.