TiO2 nanoparticles in the brookite phase were synthesized within an environmentally friendly method by magnetized water obtained by the US-patent magnetizing device (US10507450B2), which changes the properties of all types of the solvents with no limitation (protic or aprotic). Furthermore, this study is the first report on the synthesis of brookite TiO2 nanoparticle through magnetized water at room temperature. The procedure was tested by five different water; ordinary, 15, 30, 45, and 60min-magnetized water. The products were analyzed by various techniques including XRD, FESEM, ICP, BJH-plot, t-plot, Langmuir plot, BET, TEM, and FTIR. The result showed that the products obtained from 30 min-magnetized water were the most properly indexed TiO2 brookite phase with high surface activity. This sample could be a suitable green photocatalyst.