Preheat your oven to 350 degrees.
Grease a 13 X 9-inch pan with butter or cooking spray
Dump the peaches and juice into the pan.
If desired, cut the peaches in half to make the pieces just slightly smaller.
Add cinnamon over peaches
Pour the cake mix evenly over the peaches.
Cut the butter into small pats and arrange evenly over the cake mix.
You can also mix the peach juice with the mix a little, just so you won't have spots of cake mix on the top. I think if the mix is spread evenly enough, it will bake more evenly.
Bake for 45 to 50 minutes, or until the peaches are bubbly and the top is golden brown.