A process for reacting titanium tetrachloride vapors with oxygen to produce titanium dioxide wherein the oxygen is introduced into the reactor in at least two points. The process has the ability to control properties, such as particle size, of the raw pigment produced. The temperature of the oxygen introduced to the reactor at the further inlet point is above, below, or at the same temperature of the oxygen introduced at the first inlet point. The further inlet point can be located before or after the all the titanium tetrachloride has been introduced into the reactor. The titanium tetrachloride is introduced at a relatively low temperature, below about 427 C., and the reaction temperature in the reactor is at least about 700 C. The process includes the use of an auxiliary fuel such as carbon monoxide, methane, propane, butane, pentane, hexane, benzene, xylene, toluene, or combinations thereof for increasing the temperature in the reactor. Still further, the process for producing titanium dioxide provides for the addition of aluminum chloride to the reactor. Advantageously, the process allows the pressure in the reactor to be above atmospheric pressure and range between about 0.15 MPa and 4.0 MPa above atmospheric pressure during the production of titanium dioxide. A reactor is also provided with an aluminum chloride generator for heating the titanium tetrachloride and delivering aluminum chloride to the reactor.