In this study, the decolorization, dearomatization, and mineralization efficiencies of different advanced oxidation processes (AOPs; namely O-3, O-3/Fe(II), O-3/Fe(II)/UVA, and O-3/TiO2/UVA) were investigated for the azo dye C.I. Reactive Red 194 (RR194). The effects of pH (3-11), amount of TiO2 (0.05-1 g/L), and concentration of Fe(II) (0.1-1.6 mM) were investigated for the applied methods. The decolorization and mineralization efficiencies of the photocatalytic ozonation system (O-3/TiO2/UVA) were increased by decreasing the pH of the dye solution in contrast to the ozonation system (O-3). Decolorization of RR194 was increased in the photocatalytic ozonation system with an increasing amount of catalyst however, a decreasing was occurred for the homogeneous catalytic system (O-3/Fe(II)) when increasing the concentration of catalyst. The decolorization efficiency of the homogeneous catalytic system (O-3/Fe(II)) was enhanced when combined with UVA light. In our study, the most efficient method for dearomatization and mineralization was the O-3/TiO2/UVA among the applied AOPs.