I've seen this chair in many places, for instance
(there are other places as well)
It looks like a fairly common design, though I can't find who invented it not when nor what it was named.
I'll try to describe it briefly: an iron hoop at - maybe - 45º, with leather stapled over/around the upper and lower sections of it (though not always a single piece of leather), raised from the floor by hairpin legs (the same iron thickness of the iron hoop); the leather pieces are kept streched by another part of the iron structure that lies beneath the hoop; all the iron structure is painted (usually black) and are mostly naked (the only covered parts are the upper and lower sections of the hoop); particularily the naked sections of the hoop serve as armrests.
(I can't create tags yet, but I would like to tag it "design-identification", "designer-identification", "chair", "armchair", "furniture")