It won't work as a complete chicken feed / their only food, but is fine as a treat. You might check what the brand is you have, but usually it is 98% oats and 2% molasses or so, usually consider it as a treat because of the molasses even if it isn't that high in some versions. They usually recommend limiting treats to about 10% of their diet. Oats are a popular chicken food but they are not that high in protein.
Definitely follow that link that Kelsie has provided. Too much molasses can cause diarrhea and the sweetness of it can throw off the crop can cause slow or sour crop. So be careful with too much molasses. This is fine for a treat, but for the health of your birds, hatchery stock or pure bred show birds, they need to be on a good chicken feed diet.