Rúgbrauð, Icelandic Rye Bread or Thunder Bread is a traditional Icelandic bread made from rye grains, has been the most popular bread in Iceland for centuries. The reason for its popularity is because rye grains were cheap and readily available, and it was made using sourdough which was the only raising agent available. Before it was trendy, sourdough was the traditional method of fermentation and was used to make the next loaf. Until the early 20th century, households didn’t have ovens and instead, the bread was cooked in pots over stove embers from the evenings cooking.

Instead of using sugar, the bread relied on the low heat and long baking time to produce sweetness. With the invention of the electric oven and the availability of rising agents, people began to use sugar or syrup to shorten the baking time. However, in recent years, the popularity of rye bread has declined, and today, the annual import of rye is around 3 kilograms per person, while white processed flour is now the most popular bread in Iceland.


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One of the best things about rúgbrauð is that it is incredibly simple to make, even for those who are not experienced bakers. Unlike other breads that require yeast and kneading, rúgbrauð is made by simply mixing all the ingredients together.

In the past, the dough for rúgbrauð was traditionally shaped in empty milk cartons and then buried near natural hot springs to be cooked by the geothermal energy in the ground. This was possible due to Iceland’s ample use of renewable energy sources, with two-thirds of their energy coming from geothermal.

Although milk cartons have been mostly replaced with sealed tins, some families and local cafes still continue to make bread using this traditional method. The slow and long baking time in an oven, which is a result of this traditional origin, is a labor of love for a day spent at home or even better overnight so it can be enjoyed as fresh bread for breakfast. This traditional method of baking bread is a unique way to experience Iceland’s rich culture and history.

Rye flour, which is used to make Rúgbrauð, contains very little gluten compared to other flours, resulting in a moist and dense texture. In modern recipes, some whole wheat flour is often added to make the bread a bit softer and less crumbly.

To fully experience the traditional taste, Rúgbrauð is best enjoyed topped with smoked salmon or lamb. However, many Icelanders also love to eat it smeared thickly with butter, as a simple yet delicious option.



  • 3 cups of rye flour
  • 1 ½ cups of whole wheat or all-purpose flour
  • 2 ½ tsp of baking soda
  • 1 tsp of salt
  • 750ml of kefir
  • 1 cup of golden syrup


  1. In a large mixing bowl, combine the dry ingredients (rye flour, whole wheat or all-purpose flour, baking soda, and salt).
  2. Add the kefir and golden syrup to the dry ingredients. (Pro tip: coat the inside of the measuring jug with oil or butter for easy pouring of the syrup).
  3. Mix all the ingredients together until well combined.
  4. Transfer the dough to a form of your choice (we used a Quality Street tin lined with baking paper, milk cartons, or a dutch oven will also work well).
  5. Do not let the dough wait for too long before baking, otherwise, it might start rising.
  6. Preheat the oven to 200 °C and bake for 30 minutes.
  7. Lower the temperature to 100 °C and continue baking for 7 hours.
  8. You can double the recipe and freeze the second loaf for future use.

Enjoy your homemade Rúgbrauð!

Note: The long baking time is essential to achieve the traditional texture and flavor of Rúgbrauð, so be sure to plan accordingly.