Barley flour is a fine powder made by grinding whole barley grain. Along with many other flours, it can be used to replace part of the wheat flour in a recipe for a different flavor and texture. Barley flour can also be used in other cooking applications, such as acting as a thickener in soups and sauces. Many natural foods stores carry barley flour, and it can also be made at home.

Barley is a very hardy annual grain which has been grown all over the world for foods for thousands of years. Since barley is more cold resistant than grains such as wheat, it was often grown in cold regions like Northern Europe. Hordeum vulgaris, as barley is formally known, is also very drought tolerant, making it an excellent choice of crop in regions with unreliable rainfall. A number of grain products are made from barley.

When barley is freshly harvested, it has a fibrous outer layer which must be removed to make hulled barley. Pearled barley is made by polishing the barley grain even further, yielding a smooth and rounded grain, and barley flakes are made by flattening hulled barley. To make barley flour, the grain is ground in a mill.

There are two ways to make barley flour. Most commercial barley flour is made through a malting process. Malted barley flour uses whole barley which is allowed to sprout and then rapidly dry. Malting changes the chemical structure of the barley slightly, and it is also the first step in brewing. It is also possible to find unmalted barley flour, or you can make barley flour at home, if you have a grain mill. Pearled or hulled barley can both be used, although malted barley flour has a higher nutritional value since it includes the rich hull of the grain.

Like other flours, barley flour can go rancid. It can be stored in a cool dry cupboard for one to two months, or in a freezer for three to four. When barley flour is kept in the freezer, cooks can measure out the amount that they need to warm to room temperature, and put the rest back in the freezer. In yeast breads, the nutty flavor of barley flour can replace up to ¼ of the regular flour, and in quick breads and other baked goods, it can be used to replace up to ½ of the flour called for by the recipe. Barley flour has a weaker gluten than wheat flour, so baked goods may turn out strangely if too much barley flour is used.