- In Chapter II, Thaler sells one.
- In Chapter III, found in a crate near the circle of elements inside the Salamandra base.
- In Chapter IV:
- In Chapter V, sold by the fence.
Geralt starts the game with one sun rune. Later, they can be purchased from a number of merchants, including the mysterious merchant, Haggard or Thorak in Vergen, or Falas, the Incredible Lockhart or Polycarp of Rinde during Chapter III.
To use a rune, Geralt simply drags it over to one of the rune slots on a suitable sword in the inventory panel.
Sun runes can also be used to craft yellow meteorite ore.