Preheat oven to 350 degrees. Spray a 13x9 inch baking dish with cooking spray and set aside.
In a large bowl, stir together the cake mix, eggs, water, and vegetable oil until moistened, then beat with an electric mixer on medium speed for two minutes.
Bake in the preheated oven for 30-35 minutes until top of cake is lightly browned and a toothpick inserted in the center comes out clean.