The actual location in the stage differs between the original Sonic Adventure 2 and Sonic Adventure 2: Battle: The Iron Boots are found in the Mad Space stage on the Spherical Planet. They are the equivalent to Knuckles the Echidna's Hammer Gloves. Using this Level Up Item causes Rouge to leave a pink energy trail.
Once equipped, they allow Rouge's attacks to destroy iron crates. The Iron Boots are a pair of metal heels that can be attached to Rouge's regular boots.