A new modification of Fe(III) oxide - protohematite - was produced by thermal decomposition of crystalline hydroxides and salts and by plasma chemical method. Protohematite is a metastable phase which transforms into alpha-Fe2O3 at 1100 degrees C, under pressure or mechanic chemical activation. IR and Raman spectroscopy, X-ray powder diffraction, and transmission electron microscopy were used to study the structure of protohematite. It was concluded that protohematite has unique structural characteristics. The hypothesis concerning the structure of protohematite was suggested. Specific chemical activity of the protohematite was assumed to originate from the presence of some ferric cations in quasi tetrahedral (distorted octahedral) coordination.