Potato flour

Potato flour, also referred to as potato starch is a fine textured, gluten-free flour made from cooked, dried and ground potatoes. It can be combined with other flours for bread making to produce a bread with a moist crumb. Potato four is typically used as a thickener.

As A Thickener
To substitute potato flour as a thickener you can use equal amounts of cornstarch
OR tapioca flour
OR Arrowroot

For General Baking
If you are looking for another gluten-free flour you can use rice flour
OR quinoa flour.

For Bread Baking:
You can substitute 5/8 cup potato flour for each cup of all-purpose flour.