Mechanochemical effects on the formation of Mg-O-Ti complex and microwave dielectric properties of MgTiO3 oxides were studied using several different starting materials. Single phase MgTiO3 powder was obtained after heating (900 degrees C, 2 h) the mechanically activated precursor from a mixture of two unitary-powders, magnesium hydroxide and anatase (MP). Formation of MgTiO3 on subsequent thermal treatment was significantly accelerated by incipient mechanochemical interaction. The Q value of the ceramics sintered at 1350 degrees C for 2 h from MP was higher than those of three other ceramics due to the uniformity of the microstructure and phase.