Abstract: A brief review is given for the mechanism in preparing yellow tungstic oxide hydrate through homogeneous precipitation from concentrated hydrochloric acid solution,as represented by scheme 2 given in this paper. It is in contrast to the conventional method of acidification. White powdery tungstic oxide. hydrate, an active species, is prepared according to scheme4, i.e., by dropping Na₂WO₄ solution with stirring into 1M HNO₃ until pH reaches around 1,—a reversed way of acidification. The micro-crystalline white tungstic oxide hydrate thus obtained is highly active,as represented in scheme 3. Besides preparing low valent tungsten clusters, superfine WC,light sensitive WO₃·_xH₃O, and WO₃ aggregate pyridine compounds, that white tungsten oxide hydrate can also lead to the preparation of a host of metatungstates, heteropolytungstates including organoarsenic polytungstates, as revealed in scheme 3 of the above text.