Stainless steel coat hooks have a number of excellent qualities. Rust resistance is probably the one that most people think of. There's also the fact that it's a very strong material. Of course, some people just like the finishes that are available.
If your main reason for wanting stainless steel is corrosion resistance, in most instances you can use an aluminum coat hook and have many more design choices. However, if you're dealing with a saltwater environment, stick with stainless.
No matter what your reason is, here are coat hooks that meet the stainless steel requirement.
Please note there are also a few simple steel coat hooks included here which are not stainless. Most steel coat hooks are stainless, but there are exceptions. If a coat hook does not specifically say "Stainless Steel" in the title, it's merely steel. Of course, it's likely powder coated steel, which is pretty tough stuff, too.