Fe _mO _n–Fe _m–xTi _xO _n composites, complex iron oxides doped with titanium, have been synthesized by coprecipitation (Cp series) or precipitation on preliminarily obtained magnetic particles (P series) followed by hydro- or solvothermal treatment. The results of magnetometry, scanning electron microscopy, X-ray diffraction, X-ray fluorescence, X-ray photoelectron and Mössbauer spectroscopy reveal the presence of three main fractions: chemically inhomogeneous strongly magnetic particles (maghemite/magnetite-titanomagnetite), weakly magnetic particles (hematite, goethite and possibly other iron hydroxides) and superparamagnetic particles belonging to the first two fractions. Samples of the Cp series where magnetically stable particles dominate are clearly distinct from the P series, which is dominated by superparamagnetic particles. Theoretical estimations of the hysteresis characteristics based on the model of magnetostatically interacting two-phase particles are in the best agreement with the experimental data at characteristic particle sizes of 60 nm for the Cp series and 13 nm for the P series.